To me, this is what makes a good tank and I can give you advice on it:

The basics

- You hold aggro on everything unless there is a mechanic that prevents you from doing so (e.g. the boss from the extreme version of Dzemael Hold iirc doesn't have an aggro table, so it is basically just dodge aoe's and a "healer fight").

- You chain pull trash mobs (while checking on your healer's mana). So as long as your healer has mana and you have some defensive cooldowns available, then you can keep mass pulling. Don't be that tank, the one who mass pulls with no defensive cooldowns, then dies and blames it on the healer.

The intermediate stuff

- You learn the best skill rotations that will maximize your damage output, mainly on boss fights. The faster you are done with the dungeon, the happier everyone is.

- You know all the "telegraphs." By this, I mean, you know what is coming next in an encounter, you know when the boss is about to tank bust you, you know when it is doing an aoe attack that you can mitigate by using Reprisal, etc.


The advanced stuff

- Your awareness level is off the charts. You do not tunnel vision, you know exactly what is going on the entire time with your party, you use Cover and Clemency on party members who are in risk of dying to incoming damage. While I said lines above that you have to learn your best dps rotation (which for Paladins involve the use of Holy Spirit), if you notice that you have a weak healer in your party, then you want to save some of your MP to throw a Clemency here or there.

There have been countless occasions when my healer died mid fight during a boss encounter and I kept the 2 dps and myself alive by saving my mana and using Clemency on them as well as rotating my defensive cooldowns.

It is ALWAYS best to lose dps in lieu of keeping your dps alive, than letting them die because you had no mana to use Clemency. Yes, I know, it is the healer's role to heal, however, the discussion here is how to be a good Paladin tank. The dps you did by casting Holy Spirit will not make up for the lost dps of a dead dps member and the subsequent weakness (resurrection sickness) said member will have for the next 100 seconds. So just save some mana for Clemency just in case.

- You maximize THE ENTIRE PARTY's dps. What does this mean? You know where and how toposition the boss, especially for your melee dps. Remember that all melee classes have "positional attacks", which means, they do more damage if their attacks are made from the flank or from behind. If you position the boss in a way your melee dps can't attack from the flank or from behind, then you are lowering the party's overall dps. If you position the boss in a far corner of the arena when the best location is its center, then you are lowering the party's overall dps.