Brand New Gladiator here, tips....go!

[TheodoreMcIntyre]

Hmm, new to tanking also, so I also have a question -

I was under the impression (maybe I'm working with very old knowledge) that VIT was the main stat for Glad/Pali - was I wrong about this?
I'm suddenly not sure what kind of stat build I should be aiming at by lvl 50 Pali D:

You should definitely be building VIT for your PLD until you hit 50 and are at least moderately well geared. At which point you can always respec if you want. It's easy, and pretty much free, only costing some GC seals.
Personally, I have an all-vit PLD and WAR, but my WAR uses the Wave axe (CRIT/DET) and my PLD novus has its stats split between Parry and Det, with a little accuracy in there, and I don't have any trouble holding hate on most people even in all VIT gear. I also have a full i100 set of STR accessories to use in instances where I don't need all the HP.
Some of these instances include dungeon bosses and HM primals, mostly.

Really, you can split your stats any way you want between VIT and STR and still be a good tank. As long as you're not putting the points into something silly like INT, MND, or Piety.

[Rbstr]

I was under the impression (maybe I'm working with very old knowledge) that VIT was the main stat for Glad/Pali - was I wrong about this?

No, you're not wrong. It is the most important but there's a nuance to it that gets missed. Strength is also very useful for tanks as the damage they do is not insignificant and matters to their primary function of holding hate on enemies. VIT, especially when you out-gear content, can be "wasted". If you only ever lose 3k hp you don't need a 10k buffer. Strength will always add to your dps. To change the saying up a bit: You won't lose your job for carrying nothing but vit. You will, however, miss out on an opportunity to do a bit better.

When you're leveling there's no need for carrying a ton of vit around as bonus. Things just don't hit that hard and using the bonus points for strength helps you do things more quickly and hold hate against level-synced players. Make sure you've got a decent weapon and keep pretty current on the gear that carries defense and you're fine when you're leveling.
Once you hit 50, though, you open up a bunch of stuff where having the vit could really help you at lower ilevels so you should probably swap that strength to vit. If you're stepping immediately into i110ish you can easily stay 30 strength for basically anything. (And it's advantageous to use the bonus to gain strength first before swapping accessories. Accessories carry more points of vit than strength on them).

Bonus swaps are very cheap now so mess around with it.

[Alistaire]

Honestly the biggest piece of non-obvious advice is that flash enmity scales with your weapon damage. Tanks are the most gear-dependent of the roles; the better you're geared the easier your healer will have it, freeing them to DPS more if you're as geared as you can be. So more than anyone else, keep your gear up to date, especially your weapon and especially when you'll be on the lower end of the level curve for a dungeon.

[TheodoreMcIntyre]

Honestly the biggest piece of non-obvious advice is that flash enmity scales with your weapon damage. Tanks are the most gear-dependent of the roles; the better you're geared the easier your healer will have it, freeing them to DPS more if you're as geared as you can be. So more than anyone else, keep your gear up to date, especially your weapon and especially when you'll be on the lower end of the level curve for a dungeon.

Another less-obvious tip, damage mitigation buffs are multiplicative, not additive.
So if you have Shield Oath on (20%), and use Rampart (20%), you're not mitigating 40% of the damage, you're mitigating around 36%. So if you're going to pop a bunch of defense buffs, try to use buffs with effects that don't directly stack, like Rampart + Convalescence + Bulwark, or Sentinel + Foresight + Awareness. This will let you get the most out of each individual buff. If you really need to mitigate as much damage as possible, just keep in mind that when you're using Shield Oath (20%) + Rampart (20%) + Sentinel (40%), you're not mitigating 80%, you're mitigating 61.6%. Here's the math:

100 - (100 * .2) = 80 - Shield Oath
80 - (80 * .2) = 64 - Rampart
64 - (64 * .4) = 38.4 - Sentinel
100 - 38.4 = 61.6

The general formula is x - (x * y) = z, where as x = the incoming damage, y = the percentage mitigation (per buff) as a decimal, z = the resulting amount of damage you're actually taking.
So you plug in 100 for x, 20 for y (Shield Oath), and the result, z, is 80.
Then you plug in 80 for x, 20 for y (Rampart), and the result, z, is 64.
Then you just keep repeating for as many buffs as you need to math out

[Saseal]

Great, thanks for the infos! Super useful, from all of you!

I stepped into Copperbell NM last night - I was wishing my damndest for the mentioned STR (ninja + poetics BLM combo nightmare >___< No amount of flashing could save some instances). I'm going to start adding more STR for a while since, as mentioned, I'll probably be out-geared by the majority of the pugged DPS/Healers while leveling to 50. x_x

[PWilson]

Ninja + BLM seems to be the hardest party to keep aggro from. Mostly because you can't let up on the ninja's target for long at all, or they'll grab your aggro, and a BLM is dropping AOE everywhere.

[Thistledown]

Provoke had a huge range so use it to pull patrolling enemies (read: Aevis in Stone Vigil). Some patrols hit like a truck so ideally you want to be tanking them individually.

40s cooldown really is nothing so you can afford to use it on every patrol. I found 60s to be the golden standard for 'once per every trash pull'.

[TheodoreMcIntyre]

Provoke had a huge range so use it to pull patrolling enemies (read: Aevis in Stone Vigil). Some patrols hit like a truck so ideally you want to be tanking them individually.

40s cooldown really is nothing so you can afford to use it on every patrol. I found 60s to be the golden standard for 'once per every trash pull'.

Another thing you should keep in mind about provoke is that it matches your aggro to the current highest aggro and then gives you an infinitesimal amount of enmity on top of that, so if you provoke something, just keep in mind that the moment anyone does any action at all, from auto attacking to using buffs, you will lose aggro if you don't generate more.
Also, if you're looking to rip hate off of other tanks, build up to Rage of Halone, provoke, then use Rage of Halone to help keep aggro.

[Alistaire]

Ninja + BLM seems to be the hardest party to keep aggro from. Mostly because you can't let up on the ninja's target for long at all, or they'll grab your aggro, and a BLM is dropping AOE everywhere.

When you say "the ninja's target" vs BLM AoE...NIN should be doing their AoE "rotation" (quotes cause it's a rather simple setup) on 3+ targets. Since most pulls in dungeons will do that, I'd feel free to ask the NIN why he's not doing his 100 potency per target Death Blossom (so 300 potency per gcd on 3 mobs) vs his average 220 ish potency per gcd on the single target rotation. You only go to single-target moves if you're nearly out of tp.

[pforpianist]

I have some questions, some are not entirely related to the question, but it's what I've found while playing as tank in low-level dungeons (keep in mind i'm only level 25 so the highest i've been in is the mandatory Ifrit battle)

1. Can you interrupt a combo with abilities? or does that only apply to provoke? up till now i've been conscious of not breaking combos. i don't have rage of halone yet

2. This is more relevant. I've found that my gear is mostly def based, and doesn't have vit bonus on it (im only level 25) should i invest into getting better dungeon gear so as to last longer (more hp) I was intending just to go through with the storyline missions, and then focus on gear when I'm 50. Alsowhat's the best way to get higher level stuff? (20-25)

Thank you for your advice here, it's made things simpler for me, unfortunately i haven't been very good at it up till now