New Tank Advice

[Gurney]

Meld INT so Flash hits harder. Running joke with me and some of my friends when someone in the FC ask.

[Nedkel]

My advice.
Pull everything in sight and rotate your deffensive skills, always use these on trash mobs and try to avoid using two at one time instead use ane after another.
Thats it.

[LineageRazor]

Kewitt already mentioned this, but to go into a bit more detail...

Iron Will is vitally important for tanking. It gives you a steep enmity advantage over other players in your party, and will help you get and keep the attention of enemies in a hurry. The ability has no downsides whatsoever. It USED to be the case that putting on your tanking stance reduced the amount of damage you deal, and some online guides might be out of date and tell you so, but this is no longer the case. Iron Will has no damage penalty.

The only time you should not be using Iron Will is if you're in a party with another tank, and that tank is acting as the main tank for the group (with you as off-tank). Even then, it's not a terrible idea to allow the other tank to get a bit of a lead, and then put up Iron Will (in fact, some fights expect it, and will throw heavy attacks at the number one and two Enmity leaders).

As an early player, the first occasion in which you will be required to be in a party with another tank is Castrum Meridianum, one of two dungeons at the end of the original Main Scenario missions. This dungeon is easy enough that you can experiment with sharing enmity duties with another tank without a lot of danger. (There's one, even earlier optional eight-man instance, as well - the Guildhest "Solemn Trinity", which is totally optional, and the nature of the content expects both tanks to split up and take on separate groups of enemies, so it's not much different from four-man content.)

Also, keep in mind that whenever you enter instanced content that is below your current level, all of your buffs are removed, INCLUDING Iron Will. It's EXTREMELY common for tanks - even very experienced tanks - to forget that their taking stance is down when they begin a dungeon or other instance. To help combat this, I recommend you get into the habit of checking your stance whenever you enter an instance, whether it's below-level or not.

Edit: A bit on Shirk:

When you start doing multi-tank content, get used to using Shirk. It is often the case that part of the fight will require that the Off-tank and the Main tank swap places (with off becoming main, and vice versa). Use Provoke to become Main tank - and if you're becoming Off-tank, use Shirk afterwards to give the Main Tank a solid lead. It's not always necessary, thanks to the enmity bonus they added to Provoke, but better safe than sorry.

It also allows you to keep your tank stance on after a swap, since it transfers enough enmity that odds are very slim that you'll catch up and overtake the main tank.