To be honest, FF14 is not explicitly hard going, in fact, it's fairly easy in all honesty.Yet there are still a lot of common mistakes that a lot of people make that breed bad gameplay habits, as far as late end game trials such as Hard Mode dungeons and even the Binding Coil and Extreme Primals. This guide will help you unlearn those habits, and turn you from hopeless expenditure to a key team player.

Mistake One: Not Knowing Your Class.
If I had a pound coin for every single time I've ran a dungeon and there's a tank who doesn't use Flash and lets mobs aggro on the healer & DPS, let's just leave it at that I'd be very rich indeed.

Read your tool tips. Nine times out of ten, you don't and you fail to realise Impulse Drive deals more damage from behind.Understand why particular keys in your hotbar are glowing. Don't just spam Rage of Halone; build that up from Fast Blade & Savage Blade.

Ask yourself what stats need to be boosted for your class and which you can leave aside. If you're a White Mage, you don't need to put any stat points in Intelligence, Strength or Dexterity; so any accessories you wear should be boosting Mind or Piety, same with your bonus stats etc.

Mistake Two: Not Positioning Correctly.
This is something I see a lot more than people not knowing rotations, so maybe it should be number one. But I digress: as a general rule, tanks need to position the enemies so that the mob's backs are facing the DPS and the healer. And then tanks need to STAY THERE.Your job as a tank, with your increased health and defense, is to take the normal attacks face on, and only side step the BIG AoEs, and even then that's debatable depending on how good your healer is.

The reason for this is three fold:
a) melee DPS such as Dragoon & Monk get damage bonuses from hitting the backs and the flank of enemies
b) it protects your other party members from those big AoEs I mentioned
c) whilst you can dodge attacks from behind, you CANNOT block or parry them, and as a nice little bonus, you actually take slightly more damage from behind

This also means that nobody should have any reason to go around the front to where the tank is. No reason whatsoever. Now unless I'm wrong somewhere, I know of no DPS or healer skills that have a better potency from the front of an enemy.

As a sidenote: most bosses, unless explicitly stated otherwise on a walkthrough or by your party members, need to be tanked in a similar way; with them facing away from the party, and in the south of the boss arena. I've healed far too many primal matches where the tank is either tanking right in the middle, or even worse, kiting them around the arena.

Mistake Three: Wearing The Wrong Gear.
Sometimes, this ties in with mistake one with regards to knowing the class, but it also extends to wearing Disciple of Hand or Disciple of Land gear, wearing gear that is too low-level, and flat out neglecting to repair your gear.

As cool as the Foestriker's Tabard looks, if you're still wearing it when you come to Brayflox's Longstop, you're basically asking for an open casket funeral to show that off in. It's level 15, and really shouldn't be worn past level 22. As a general rule I would say the cut off is 5-7 levels above the designated level you can wear it at, THEN you should change it. Besides, you can glamour it at level 50.

Understand again what accessories in particular maximise your potential in your chosen class. As a Bard, for example, you want stuff that boosts Dexterity, so something like the Sunstone Ring that boosts Strength & Skill Speed... isn't as great as you'd think it is. (Skill/Spell Speed is a false economy anyway, sorry)

A final point: repairing your gear is a necessity, and you need to keep on top of it. Picture this; you're in a dungeon and a message pops saying "Your Steel Chainmail is at less than 10% durability". Unless you have dark matter on you and the high enough DoH job to fix it, you're SOL. Great job, dingus.

Mistake Four: Not Understanding Enmity.
Hate, aggro, enmity, whatever you want to call it - the tank gets all of it. The tank also needs to understand how to keep it too, and not share it willy-nilly with their team mates, or a better analogy, not let anyone else have it. Have your hatred cake and eat it, tank.

There's a few visual ways to understand how enmity works and how not to draw it off the tank, or if you are the tank, how to keep it.

When engaging in a dungeon, pay attention to the symbols in the list of enemies (by default on the lower left side over the chat box). Ideally, DPS & healers want this to be shown as a green circle, where as tanks want it as a red square. If it changes to a yellow or orange triangle; tanks need to pull that enemy back, and the DPS and healer need to cool it off a bit.

Other enmity symbols are on the party meter- a meter appears under the class icon of that party member that shows the current enmity on that current target, and, well, the enemy turning to face you to claw your little Lalafell face off.

But sometimes, tanks lose enmity, usually because they're not focusing on a particular enemy, or because their team mates are being overzealous with heals, buffs or damage. That's the sort of little flub that can be corrected with a quickly timed Provoke or Shield Toss, or telling your Black Mage to knock it off spamming Flare. This is also why marking is important, and why tanks should ideally mark their targets in some form of kill order.

When all else fails, the DPS or healer pulling enemies off the tank should try to move closer towards the tank - this applies obviously more to ranged DPS such as Bard or Black Mage. The enemy will follow them and often put it in range of Flash or Overpower.