What does this guide (hopefully) cover?
I'll say this right off the bat: this isn't aimed at teaching people how to heal HM Titan or Bahamut's Coil. For a start, I haven't even done the absolute endgame stuff myself yet. What I hopefully will manage to do is give some solid general advice for people to build upon. Healing in this game isn't really that difficult, but it's something that I've noticed quite a few people struggle with. Mostly that's because they're missing the small things that go a long way, such as correct MP and aggro management. I'm not going to say anything at all about solo play. Instead, I'm going to focus entirely on dungeon play, and hopefully cover enough of the fundamentals to give newer white mages a leg up.
Probably the highest concentration of important advice is at the end of the guide, so feel free to skip to there if you don't care about what I have to say about abilities and traits. However, I have tried to go into detail about how to make the best use of a skill in dungeon situations, so hopefully there will be plenty of worthwhile information there too!
Ability Overview
There are countless sites where you can see all of the details you want about how a skill works, so I'm not going to bother with that. Instead, I'm going to focus on trying to give an overview of how I've found the best way to use abilities in dungeon play is.
Stone
Deals earth damage with 140 potency and applies Heavy for 20 seconds. This is great for soloing, but I never cast it in dungeons. Heavy isn't important as either the tank will have aggro and enemies won't be moving, or someone else has aggro and they should be trying to take the enemy back to the tank as quickly as possible. Cast it for a bit of damage if you have free time in the dungeons before you get Stone II, but otherwise I wouldn't bother.
Cure
Heals target with 400 potency. This is one of your two key abilities that you're going to be spending the vast majority of your time casting. It's a small, cheap heal that you can basically cast all day long without running of MP, and should be your main response to dropping health bars that need immediate attention. It's important that you do as much of your direct healing (i.e. healing that isn't via Regen) with this as you can get away with, as Freecure is an awesome trait and one that you want to see activating a lot.
Aero
Deals initial wind damage with a potency of 50, and then applies an 18 second wind DoT with 25 potency. This is weak, but it's also cheap enough that it may as well be free damage. If you've got free time than you should be going into Cleric Stance and applying this before you start using Stone / Stone II, and even if you don't have time to go into Cleric Stance, you might as well stick it on the tank's target for a bit more damage (as long as you don't need to do anything more important).
Cleric Stance
Swaps your INT and MND, makes offensive spells 10% stronger and healing spells 20% weaker. This is another awesome soloing skill that isn't too important for dungeons. Obviously you never want to be under Cleric Stance while trying to heal; that's just asking for a wipe, especially at endgame when your MND is naturally 50% or more higher than your INT, so Cleric Stance is going to be cutting your healing to around half of what it usually is. Still, if you get free time then there's no reason not to go into Cleric Stance and help out with damage a bit - just don't pull aggro!
Protect
Increases the party's physical defence for 30 minutes. This should always be up on everyone, almost without exception (the exceptions being when you're paired with idiots that run off before you can cast it, or if someone dies mid-battle). I believe the increase is around 15%, which isn't huge but it makes a noticeable difference to how easy it is to keep people up.
Medica
Heals all party members within 15 yalms with 300 potency. In an ideal world, the tank would hold aggro and the DPS would dodge AoE, and you'd never have to cast this. However, that's not going to happen and this is your best option for quickly getting the entire party's HP back up to acceptable levels. However, be careful that you don't cast this unless you need to: it burns through your MP very quickly, and generates a lot of hate. Just remember that if you're casting Medica to heal two people at once in a four man party (you shouldn't), you generate four heals worth of hate, regardless of whether the other two members needed healing.
Raise
Resurrects target to a weakened state. Obviously this is a skill that you never want to have to use, but no matter how good a white mage you are, you are going to have to cast it much more often than you'd like. Swiftcast is a godsend with this (see further below), but if you don't have Swiftcast you'll have to find 8 seconds to cast this, which can be tough. It also costs a lot of MP, probably around a quarter of your MP bar. Casting Raise is a question of risk vs reward. As a white mage, you should have a very good idea of the rate at which everyone is taking damage in a fight, the rate at which you're burning through MP, and how much longer the fight should be lasting. If you feel that damage is coming in slowly enough that you can take 8 seconds out to Raise (this point is irrelevant if Swiftcast is available), and that you can burn through a ton of MP without making things too difficult for yourself, then go for it. If not, don't bother until after the fight. You're better off having a slightly smaller party that takes longer to win a fight than temporarily going up to a full party and then wiping because you just burned through all of your MP.
Fluid Aura
Deals water damage with 150 potency, knocks the target back 15 yalms and applies Bind for 6 seconds. This should be something that you only use very occasionally, mostly in situations where you've overaggroed and running an enemy to the tank is for some reason undesirable. However, if you're going to use this, make sure you're going to be knocking an enemy towards the tank, rather than in a completely opposite direction.
Esuna
Removes a single debuff from the target. Esuna is vital for some things, such as removing paralysis, but it's simply not worth using it to remove every instance of poison or whatever that appears. It eats through your MP alarmingly fast, and removing multiple debuffs is going to put you into GCD much more than you'd like. This is one that you simply get a feel of when you use once you're familiar with the majority of debuffs. It should also be noted that it doesn't remove every debuff - I'm not aware of a comprehensive list of what it can and can't remove, but you should learn to recognize what can be removed pretty quickly.
Stone II
Deals earth damage with 170 potency. This is basically better than Stone in every way for dungeons, and actually puts out decent DPS when under Cleric Stance. Feel free to spam it if the party is against harmless trash mobs.
Repose
Puts a target to sleep for 30 seconds. This is a fantastic ability that a lot of white mages don't use anywhere near enough. In an organised party, you'll hopefully be coordinating what you sleep in advance, but even in a PUG Repose can make your life a lot easier. If you aren't coordinating sleeps, just take a few seconds to watch the battle and sleep anything that the tank isn't targetting. Hopefully your DPS will be focusing down the tanks target so your sleeps won't be broken, but if you find that your sleeps are consistently being broken then just stop casting it, it's a waste of MP.
Cure II
Heals the target with 650 potency. This is a very important skill, but also one that you have to be careful with. If you're doing a good job of healing as efficiently as possible, you're going to be getting Freecure procs pretty regularly. When you see a Freecure proc, you should be aware that you can cast this without worrying about the MP cost. However, it's better to miss out on a bit of MP efficiency by letting Freecure expire than overhealing for the sake of using it and risking drawing aggro. If you don't have Freecure, then you have to be very careful about using this - it's another skill that can burn through MP very quickly. I basically only use it without Freecure when I'm required to quickly deal with spike damage and I'm not confident that Cure will be enough.
Stoneskin
Applies a 30 minute shield to the target that blocks damage equivalent to 10% of their maximum HP. This is another spell that you want to be careful with. Before each engagement you should be applying it to the tank(s), and if you have any downtime then you might as well apply it to the entire party seeing as it lasts such a long time. However, you should mostly avoid using it in battle, as it costs the same as a Cure II but is usually less efficient (and remember that Cure II itself is inefficient enough that you want to avoid overusing it). There are, however, a few good uses for it outside of prebuffing the party. Stoneskin prevents damage instead of healing it, so it doesn't generate hate like healing does - that means that if you're on the verge of pulling aggro, you don't have to choose between doing nothing and pulling aggro. It's also very useful against bosses that have strong AoE attacks. In the boss battles that use AoE attacks as their main mechanic, you'll often be able to see when someone in your party looks like they're going to be hit by one and throw a Stoneskin their way before it happens. Stoneskin also works pretty well with Regen, and even though it's an inefficient way of doing things, against trash mobs I'll sometimes (especially with a high HP warrior) apply regen and then just keep applying Stoneskin once it ends so that the warrior can focus on their job instead of worrying about a HP bar that's bouncing around.
Shroud of Saints
Halves your hate level with all enemies, and applies a MP refresh effect with 60 potency for 15 seconds. Good use of this skill makes a huge difference when it comes to preserving your MP over longer, more intense battles. You should be hitting this as soon as your MP drops low enough that you'll be get the full effect from it - if your MP returns to 100% before this ends, you're essentially wasting the MP that it hasn't yet restored. I can't really give generic guidelines as to when that should be, as you should have a good idea of the rate at which you're using MP. The reason to try and time it to be as early as possible is to get a head start on its cooldown - getting your first use of it off nice and early increases the likelihood that it'll be available towards the end of the fight when you're probably going to be needing it, while still giving you as high a total MP pool for the fight as possible.
Cure III
Heals the target and all allies within 4 yalms with a potency of 550. Unfortunately, this kinda sucks. The AoE heal is over far too small an area for it to proc with any regularity (and basically never if your party is positioning themselves probably), and it costs a ton of MP. If you notice a melee DPS bunching up with your tank while they're both damaged then it can be an OK way to get them both up immediately without generating hate by casting a bad Medica, and if you get an Overcure proc from Cure II then it's occasionally worth casting this for the guarenteed crit heal on a tank in response for spike damage, but that's incredibly rare (in an ideal world, you'll only be casting Cure II when you've got Freecure, which procs on 15% of Cures, and you'll only be casting this when you've got Overcure, which procs on 15% of Cure IIs, so you'll have a 15% window in which casting this is worth it on average once every 45 Cures).
Aero II
Deals wind damage with 50 potency to a target and then applies a wind DoT with 40 potency for 12 seconds. This is another one that you'll just be throwing out under Cleric Stance when you've got free time. It's our best DoT for quickly throwing damage onto trash mobs as it deals its potency over a shorter space of time.
Medica II
Heals all party members within 20 yalms with 200 potency, and then applies a HoT with 100 potency for 15 seconds. Once you hit 50, this should take over from Medica as your main party heal as it's much more efficient - from this point onwards Medica should only be used in response to a bunch of party members getting dangerously low from AoE damage and requiring immediate attention. This also has a wider range than Medica, which is extremely useful for making sure it hits everyone. Still, it suffers from the same problems that Medica does in that it generates a lot of hate and burns through your MP extremely quickly.
Presence of Mind
For 10 seconds your spell speed is increased by 15%. Obviously this is nice, but I rarely find that I really need to use it. You might as well hit it as you cast Cure II if the tanks HP has dropped below 40% or so to be safe, but it's not a key skill.
Regen
Applies a 150 potency HoT to the target for 21 seconds. This is, along with Cure, your most important ability. It's by far your most efficient single target heal, and it makes a noticeable difference in how easy it is to keep someone alive. Generally when going through a dungeon, this is the first thing I cast on the tank after Stoneskin runs out, and it's my main way of bringing up party members who've taken a reasonably large hit but aren't taking any significant further damage, for two reasons: firstly, it's the most MP efficient way of healing them up (apart from waiting until everyone needs healing and using Medica II); and secondly, it casts instantly, so instead of spending 2 seconds casting Cure on them, you can spend 2 seconds repositioning yourself for the best view possible. Regen is also a great way of dealing with unavoidable party-wide damage. Two examples that spring to mind are the Titan fight, which suddenly becomes a lot easier if you do it at level 35 because you can more or less maintain Regen on the party indefinitely to deal with his AoE, and the first and final bosses in Aurum Vale, where Regen will counteract the damage over time effect while you wait for it to reach enough stacks for you to eat a fruit.
The is one thing you'll have to watch out for with Regen though: it's very good at pulling aggro. There are two situations in which you're most likely to see this. If your Regen from the last battle is still on the tank when they pull, chances are the mobs are going to run straight past the tank and go for you. That shouldn't be happening seeing as tanks can just right click off Regen before pulling. Needless to say, don't prebuff with Regen before battles. The second situation is during boss battles with regularly spawning adds. If you have an active Regen when adds spawn, they're probably going to target you. There's not a great deal you can do about this, just deal with the aggro in the appropriate way (see the aggro section later on).
Divine Seal
For 15 seconds, cure magic potency is increased by 30%. It's pretty obvious when you want to be using this: when your normal curative spells aren't quite enough to keep people up. You can achieve 25% uptime on this, but you're probably going to be better off saving it for when you need it most rather than using it on recharge to attain maximum efficiency. The two main uses for it are casting it before Medica / Medica II in order to get out a huge party heal, and casting it before Cure II in order to bring a tank back up after spike damage. It's also worth refreshing Regen on your tank when this is up; even if you cast Regen a second before Divine Seal ends, Regen will have increased potency for all 21 seconds that it's in effect.
Holy
Deals 250 potency of Holy damage to all enemies within 8 yalms of you and applies a 4 second stun. Apart from it looking really cool, the main reason that I've used Holy is to pump out AoE in FATEs (Dark Devices) and get a ton of experience. I'm sure there are situations where it's awesome in group play, especially in dungeons where you're in no danger of taking deaths to trash mobs and pumping out AoE is going to speed things up, but so far the only time I've used it in dungeons is in the easy part of the Praetorium. Just be careful about how you use it. Not only does it burn through your MP incredibly quickly, but it's going to draw a ton of hate too.
Benediction
Restores all of the targets HP. This is your "oh shit" button, and it's not something you should ever be using until it's needed, even if it's a free full heal. The cooldown is simply too long for it to be worth it (unless you're really feeling the pressure and can't find enough MP to cast Cure / Cure II), as you'll never know when you might need a panic heal. The main use for this is to bring a tank back up after spike damage, or to heal another party member if they've taken a massive hit and pulled aggro.
Traits
Our traits are all pretty obvious really, the only subtleties come from working out how to make the best use of Freecure and Overcure.
Proshell
Protect now increases magic defence as well as defence. This is obviously great, and makes Protect worth keeping up even more than it already was.
Enhanced Raise
Raise can now be used in battle.
Freecure
There is a 15% chance that upon casting Cure, for 15 seconds your next Cure II will cast for free. Keeping track of this is one of the single most important things about playing white mage effectively, and making effective use of Freecure goes a long way towards helping you to effectively manage your MP. Relying on Cure as your main direct heal and, as much as possible, only using Cure II when Freecure is available is one of the best ways to stay on top of MP management.
Graniteskin
Stoneskin now blocks 18% of a targets maximum HP instead of 10%. Obviously this is a big improvement, almost doubling Stoneskin's efficiency. I wouldn't ever cast Stoneskin in battle without this trait.
Overcure
There is a 15% chance that upon casting Cure II, for 15 seconds your next Cure III will heal critical HP. As I mentioned in my overview of Cure III, there are rare occasions in which this is nice, but unfortunately they're so rare that this is essentially useless.
Enhanced Shroud of Saints
Increases Shroud of Saints refresh potency to 80. It's a small increase, but more MP is always a good thing!
Cross class abilities
There isn't really any debate to be had when it comes to cross class abilities. White mages are allowed to choose five of them, and we have seven to choose from: Ruin, Physick, Thunder, Surecast, Virus, Swiftcast and Eye for an Eye. Ruin is bad and Physick is a clone of Cure (which is actually considerably worse due to not being effected by Freecure), so that leaves five skills for us to pick.
Thunder
Deals 30 initial lightning damage, and then applies a 40 potency lightning DoT for 12 seconds. You'll be using this a lot for soloing to improve your kill speed, but its role in group play is minimal. If you've got free time then you can throw this up with lower priority than Aero and Aero II.
Surecast
For 10 seconds, the next spell you cast can't be interupted. This is occasionally handy, but most of the time interrupts aren't a big deal for white mages. It's worth using before casting Raise if you either haven't got Swiftcast yet or it's on cooldown. It's also nice against bosses that have unavoidable AoE; you can hit Surecast and start casting Medica so that it finishes just after the AoE hits, which can occasionally be a useful thing to do. Otherwise, it's not really a spell that I've got a prescribed use for; I just hit it when I find myself thinking "an interrupt here would be really bad".
Virus
For 10 seconds, the target's STR and DEX are reduced by 15%. This isn't really a hugely important ability, but it doesn't cost MP and casts instantly, so you might as well use it on bosses for a bit of damage reduction. If you can coordinate chaining it with other members of your party then it's going to be more useful.
Swiftcast
For 10 seconds, the next spell you cast is cast immediately. This is by far our most important cross class ability, if only because it allows us to effectively use Raise in battle - not having to find 8 seconds where you can safely stop healing to Raise someone is huge. It's got a few other uses such as instant cast Medica to recover from AoE attacks, but Raise is the main use for this.
Eye for an Eye
For 30 seconds, there is a 20% chance that when the targeted party member is struck, they take 10% less damage. This is another that's not going to have a hugely noticeable effect on how well you perform - it's a 2% damage reduction on average - but it's free so you might as well throw it on the tank for harder fights.
Playing as a white mage
With the abilities out of the way, let's get onto what's really the important part of the guide: how to effectively play as a white mage. At the most basic level, playing as a white mage involves effectively managing three things at once: your parties health bars, your own MP bar, and your enmity bar. In other words, you want to keep everyone healed up without running out of MP or drawing aggro. As long as you're able to do that, you'll be a good white mage and I doubt you'll get any complaints from the groups you play with.
How to divide your attention
A lot of white mages literally sit and stare at the party's health bars for the entirety of every single battle, and end up getting tunnel vision and becoming more or less oblivious to what's going on around them. You can get away with that in most battles, but against bosses a lot of players that do this suddenly find that they can't keep up with where the boss is, dodging its attacks, and keeping the party alive.
A big part of playing a white mage as well as possible is being able to anticipate where damage will be coming from in order to avoid being taken by surprise and forced into making a rushed, probably sub-optimal decision about how to react because a health bar just dropped out of nowhere. In order to do that, you need to watch the battle at least as much as you watch health bars (and probably a lot more). You need to keep track of where your party members are, and particularly knowing who looks like they're in danger of being caught in a bad position. You also need to keep track of the enemies. If you see a boss throw down a red cone in the direction of your dragoon, you should be ready to cast Cure, just in case they don't dodge it in time. In fact, it's often possible to see in advance when somebody isn't going to dodge an attack in time and get ready to deal with it.
Learning to divide your attention between the battlefield and the party list is one of the more difficult things to get used to, but it's really not that hard with a bit of practice. At first, you're going to want to watch the battle, but constantly force yourself to look over at the party list every 1-2 seconds to make sure everything's OK. That's stressful at first, but it doesn't take long for you to begin to do it automatically, and eventually you'll find that you're able to effectively do both at once without even trying. Having a good UI setup helps a lot here, see my UI comments a few sections down.
Positioning
I'm not actually sure that my usual positioning is the kind of positioning that MMO veterans prefer, as it's heavily influenced by healing in PvP games where you want to stay back and avoid damage as much as possible. I haven't had any real problems with it though. Generally speaking, in standard battles against trash mobs, you should stay back at almost all times, towards the far edge of your spells range. Following on from my last point, your aim is to make sure that you have as much vision of the battle as possible, making sure you know where everyone in the party is and how much danger they're in, while being in range to quickly heal someone if needed, and ideally being far enough back from the battle that you aren't forced to constantly reposition yourself to avoid AoE. You should also try to avoid being close enough to other party members that if an AoE attack is thrown your way it'll hit more than one of you. Here's a diagram of how I'll generally position myself. T is the tank, M is melee DPS, R is ranged DPS,H is the healer, and E are enemies.
........E T E...
..........E.....
..........M.....
................
..............R.
......H.........
I've found that sticking to that kind of formation as much as possible lets me have the best view of the battle to keep on top of what's happening. It should go without saying, but you're obviously going to want to reposition yourself to stay in range and continue to have a good view as the battle moves about.
For bosses, sticking to a rigid formation generally isn't going to be possible, as you're going to be forced to move about a lot more in order to dodge attacks. However, the same principles apply: you want to stay in range of your party and have a good view of what's going on at all times.
Knowing your party and getting a read on the battle
Knowing your party will obviously be harder if you're a duty finder PUG, but you can still get a reasonably accurate read on what people are like within a couple of engagements. Know how the tank likes to pull, how good he is at maintaining aggro on enemies other than his primary target, and roughly how good his gear is (is he taking a lot of damage from auto attacks? Hopefully not, but occasionally you get undergeared tanks and will have to work harder). Know if you've got a melee DPS that likes to get out of position and eat AoEs; you'll have to keep an eye on them. Know if you've got a ranged DPS who's good at pulling aggro. In 8 man content, know which tank is doing most of the tanking, and know about the second healer. If they're a white mage, keep an eye on their action bar at first to try and get a read on how they react to situations - if they're proactive about topping off health bars with Cure, then you can focus more on casting Regen, as you both casting Cure whenever someone drops to 70% is a waste of MP. If they're reluctant to use Medica, even when it's a good idea to do so, and try a bit too hard to individually heal everyone up, then you can take the initiative and use Medica as needed.
Managing your enmity
Healing generates a lot of hate, and you're going to end up pulling aggro every now and again, even if you're doing a good job. Most of a white mage's aggro management comes from correct use of skills and not overhealing - there's no need to cast Cure every time someone drops to 90%, or Cure II when a Cure would be enough, there's no need to maintain Regen on people that aren't taking damage, and there's no need to cast Medica unless the party has taken a reasonable amount of AoE damage.
If you do find yourself generating too much hate, don't forget that you have Shroud of Saints. It's mostly used as a MP management skill, but halving enmity on all enemies is awesome too. You've also got the Stoneskin option that I mentioned earlier - if it's an easy battle that you won't have MP issues in, you can just keep casting Stoneskin on the tank while Regen handles their healing to make sure you barely generate any hate, but that's only really an option against trash mobs. One thing to watch for is pulling aggro in the first few seconds of an engagement. You should be starting by casting Stoneskin on the tank as they run to the mobs to pull, which gives you a few seconds of not having to worry about healing. Even if they start taking a bit of damage, wait a few seconds before casting Regen to make sure they've got the aggro firmly under control. Hopefully your tank will be using Flash, it's safe to cast Regen once you see Flash go off. You should absolutely never precast Regen before at battle, as it's going to generate a load of hate to start the fight off before things are settled.
Finally, when you do pull aggro, don't try to kite, because you'll mess things up for the rest of the group. Just stay calm and run to the tank so that they can take aggro back from you, and then retreat to your preferred position once you've lost aggro.
Dealing with common situations, MP management and avoiding panic
Apart from drawing aggro and reacting to dangerous situations badly - for example a four man party being brought to 40% by AoE and deciding to cast Cure II four times instead of Medica once, the number one problem for white mages seems to be running out of MP, which is very easy to do if you aren't healing efficiently. I've already given a lot of general advice about efficient healing in the ability overviews, the essence of which was: do as much healing as you possibly can with Regen, use Cure to do as much direct healing as you possibly can, try and avoid using Medica / Medica II too often, but definitely use them when you're going to get your MPs worth, don't use Cure III outside of execptional circumstances, don't bother overusing Stoneskin in battle, and don't overuse Esuna. The reason that white mages overuse their expensive abilities and run out of MP is that they panic. They see a tank take spike damage to 50% and immediately hit Cure II, or they see an AoE go off and immediately hit Medica, and before they know it they've burned through their MP reserves and are stuck casting Cure and Regen without the option of using a more powerful spell when they need to. A lot of this follows on from my previous point - if you've got a good read on the battle, you're going to know roughly how much damage can be dealt to your party over a certain period of time, and that will help you make an informed decision on how to react - you'll know when the tank's in danger of being focused down and needs a Cure II, you'll know when it was a one-off hit and you can just use Cure, and you'll know when things are fine and you can let Regen bring them back up. Most cases of the white mage panicking stem from them not knowing what's going on. Once you're used to being aware of what's happening in the battle, you'll find that it's a lot easier to calmly make the correct decision about how to react to a situation.
Shroud of Saints is incredibly useful at helping with your MP, and you're going to want to use it as much as possible in boss battles. You should be using it as soon as your MP is low enough that you're not going to be wasting the MP regen, in order to maximise your chance that you'll be able to use it a second (or third, or fourth etc) time in the fight should you need to. Each use of Shroud of Saints is effectively increasing your total MP pool for the fight, so you need to find a balance between using it as many times in a fight as possible and not wasting its uses.
If you've got a bard in the group then you're in luck as mage ballad basically gets rid of your MP management issues completely. However, there are still a few things to watch for. Firstly, don't take that as an invitation to spam Cure II, Cure III and Medica to your heart's content - you'll just end up drawing aggro. Secondly, communicate. If your bard put up mage ballad without you asking for it but you're finding that you don't really have MP issues, let them know that they're welcome to drop it and do a bit more damage if they want. Conversely, if your bard isn't using it against a tough boss and you can see that you're running out of MP, ask for it. Every bard I've played with has been happy to turn it on to help avoid a wipe. Just don't wait until you're down to scraping enough MP together to cast Cure to ask for it, as that's probably going to be too late. You should know how fast your MP is going, if you can see you're going to run out early, ask for it even if you could go for another minute or so.
Dealing with blame
As a white mage, you're going to be blamed for a lot of things, some of which are actually your fault and some of which aren't. However, there's no point getting worked up about being blamed for a group's failings. Instead, you should look at each situation objectively and ask yourself whether there was anything you did obviously wrong, or whether you could have done anything better, and then try to work on that in your next group. If you ran out of MP, was it because you overused inefficient skills, was it because you weren't using Shroud of Saints, or was it because your team was taking far too much avoidable damage, such as from standing in red circles. If you consistently drew aggro, ask yourself why. Were you overhealing? Were you using Medica to heal a few people instead of the entire party? Was your group taking so much damage that you were forced to spam Medica? Or was your tank just not doing their job properly? If your tank died, was it because you reacted too slowly to cast a heal that you really should have got off, was it because the tank overpulled, or was it because the tank is badly geared? If you're honest with yourself each time something goes wrong, you'll quickly learn to correct your mistakes.
Setting up your UI
This is closely related to the section on how to divide your attention - you should know what you struggle with and try to optimise your UI to help you deal with that. For example, I find that my right eye is my dominant eye, so I'm naturally more comfortable looking at the right of the screen than at the left. To deal with that, I've reorganised my UI so that the important information is grouped in the right of my screen, and then I can position myself and the camera so that the battle is in the centre, just to the left of the party list, the enemy list and the minimap. That minimizes the amount of the screen that it's critical for me to keep track of and makes things a lot easier. Here's a screenshot of my UI - I'm not saying it's great (in fact it's far from great, but I'm limited in what I can do by playing at a relatively low resolution to increase FPS), but hopefully it's a good example of how I've tweaked things to make them easier for me.
The idea's pretty simple: everything important on the UI is grouped to the upper right corner of my screen, which means I have to divide my attention as little as possible.
Tips for tricky fights
I'll probably add a few more of these in a few days, but for now it's just going to be tips for Garuda. I figured I might as well repost them here seeing as I'd already posted them in another thread. I'll rewrite the Garuda tips to overlap with the rest of the guide a bit less at some point too.
Garuda (normal)
Garuda is pretty easy to heal compared to a lot of the boss fights really; the "difficulty" comes from her attack at the end of the first stage based on how many rocks remain.
The arena's set up roughly as
...1
2 ... 3
4 ... 5
...A
where the numbers are rocks and A is her first teleport location. If the tank gets her facing 1, the melee dps are behind her, and then the healer and ranged dps spread out around the right of 3, far enough apart that her ranged aoe attack only hits one of you and far enough from 3 that it isn't hit by her ranged aoe, then you can heal almost all of the first half of the fight just by maintaining Regen on the tank + putting it on anyone that needs it, and maybe throwing out the occasional Cure. That means you should be free to watch the battle for the most part, just throw a glance at the party list every couple of seconds to check if you need to heal. Then when she teleports, you'll easily see it because you aren't starting at health bars. Run to the bottom side of 3 to dodge the attack, when she's used it turn 180 degrees and she'll be in the mirror position of 1 at the bottom (but no rock here, A on my diagram). Same process repeats, but this time when she teleports you put 5 between you and her. This time she'll pop up in the middle, make sure everyones healed up. Around this point you're probably going to be at about 60% MP, hit a Shroud of Saints around that point to get back to practically 100% and get a head start on the cooldown. After the third round of feathers, stay close to 5, hit a Medica as soon as you're hit by her big attack (the one based on how many rocks are left, as long as people aren't standing next to rocks and letting her damage them you should only really have lost a couple of stages of rock in total).
For the second phase, let the tank get things under control while you stay on the edge of the circle away from her and the tank and Medica up as needed to recover from her big attack. You'll still have a ton of MP at this point and Shroud of Saints should be well on its way to being available again, so MP shouldn't be an issue for the rest of the fight - most importantly if you've been careful about saving MP for this point by using Regen as much as possible, you'll be able to afford to spam Medica a lot more than normal should you need to. The only thing you have to watch for at this point is when she flies to rock 1, at that point get to the very edge of the circle between 4 and 5, as far away as possible from here, and you'll minimize the damage she does, Medica up and you should be good.
It's not too hard really. In fact, DPS are probably more important than the healer for Garuda seeing as they need to take down feathers fast. Just try to get into the habit of watching the field at least as much as you watch health bars (you pretty quickly get used to watching both at once) and the only time you're likely to get a death is if someone isn't dodging attacks properly. I suppose if you're really struggling and still using the default UI (party list on the left), you can reflect my positioning horizontally (so you're spreading out to the left of 2 instead of to the right of 3) which will let you have a good view of the field while keeping the tank + Garuda right next to everyone's health bars. All you really need to see at first is when she teleports; it shouldn't be too hard to miss a huge primal suddenly disappearing from right next to the health bars.
TBH, if your DPS are struggling to take out feathers (especially the third set, which is generally the one that people mess up on), you can probably afford to throw out a Holy or two as long as everyone's health is relatively stable.
Oh, and a final thing: apart from before the initial engagement, don't bother putting Stoneskin up on anyone once the fight's started. It costs as much as Cure II and is generally going to be less efficient. Even if she's hitting you or a DPS for ~900 damage before the tank can get things under control, just throw a Regen up and let them recover. I never found that she targeted a non-tank twice to start, so just let Regen do your work for you as much as possible; it's by far your most efficient spell.