it's a long road. it goes like this: 1. keep aggro, 2. mitigate damage, 3. position mobs/know the dungeon.

1. If you're in a low level dungeon where you don't have shield oath, don't fret if you lose aggro. There isn't much you can do against a red mage spamming scatter and at that level, the dps can take some hits. For anything else, make sure you're in shield oath and use flash. Add your enmity combo. You won't have any problem keeping aggro.

2. Now that you have all the aggro, you may take so much damage that you drop like a rock. Use your cooldowns. A tank that saves cooldowns for an emergency usually causes those emergencies. Try to rotate your cooldowns so you're smoothing out your damage intake. Use Rampart (role skill). Use Bulwark. Use Sentinel. Use Convalesce (role), and Reprisal (role).

3. On top of just doing your job as tank (keeping threat and mitigating), you're required to do one more thing as tank: know the dungeon. People expect you to know where you're going and to know what you're doing with the enemies and bosses. Watch out for patrols in ARR dungeons. That primarily what makes places like Aurum Vale, Stone Vigil, and Dzmael Darkhold to hard to tank. There you are minding your business and a wandering aevis comes over and wrecks your group. Don't face telegraphs at the group. You face the telegraph from the last boss morbol at the healer, then the healer gets all the debuffs... and you wipe.

Extra credit. Bring items! Bring potions to heal yourself, antidotes to cure your own poison, and spine drop to cure paralysis (i see lots of healers get paralyzed from the chimera boss at the end of cutters cry, then they can't heal). you can items on other players, so long as you're in melee range (but not potions).