How do I tank and how do I heal?

[synesthetic]

First off, make sure you understand how initial aggro and enmity work.
If a monster's name is in yellow, it's not attacking anyone.
If a monster's name is in orange, it's attacking someone, but it's not "claimed" yet.
If a monster's name is in red, then it's claimed by someone in your party. (Purple would be when it's claimed by someone outside of your party, but that's not relevant to what I'm going to say.)
The first person to get that monster's name in red also gets some bonus chunk of initial enmity, and it's important that it be the tank who gets this, especially when you're low level or have a small weapon. If someone else gets it, it can make the tank's job a lot harder.

There are two ways to get claim on a monster.
1) Do damage to it. An exception to this is GLD's Flash, which does no damage, but can still claim.
2) Buff/Heal someone on the monster's enemy list.

In dungeons, if the tank runs up to a mob, the mob will only have the tank on their enemy list at that point. If the healer casts on the tank before the tank can hit everything, then the healer will get claim. The same will happen if a tick of Regen goes off before the tank can act, so WHMs learn to not apply Regen before pulls.
So as a tank, your first priority is to hit everything as soon as possible with either Flash or Overpower, as both of them are AoE moves with bonus enmity. If you're after a single target, or you need to pull from a range, Shield Lob or Tomahawk is your go-to, followed by Flash/Overpower if a mob came with it.

After that, against one target, your main damage combo is also your best way to generate enmity against a single target.
Against two targets, you can alternate which one you hit to keep aggro on both.
Against three or more, Flash/Overpower at least once in a while to make sure the healer doesn't pull aggro just from healing. If you have DPS that AoE though, then use Flash/Overpower more, and if your weapon is good enough against theirs, you should be able to keep everything off of them. When I AoE and pull aggro, and I see that the PLD still has over half of their MP bar, I know they didn't try.


For Protect, it hits everyone in a wide AoE around your target (or yourself if you're targeting nothing or a monster).
On PC, you can target party members more quickly by either hitting F1-8, or clicking on their name in the party member list. I don't use a controller, but I believe for them it has something to do with the left analog stick? Left/right or up/down, one of them goes through the party list, the other goes through the enemy list?
Once you get a good feel for how much you can heal, it shouldn't be too difficult to keep everyone in your party alive. And if your MP can support it, over-healing isn't too bad really.

For getting xp outside of a dungeon as a healer, you need to actually do something to monsters to get xp from them. Tag everything with Aero or Bio. It's unfortunate that you can't just focus on only healing in FATEs for xp, but that's how it is. If you at least tag a boss though (and make sure it hit), then you can heal as much as you want after that.