TANKS
- Please avoid AoEs. This is the most recurring problem in every dungeon or trial, tanks and dds not avoiding AoEs. When you get hit, even if you may not realize it, the healer(s) have a really hard time healing you, because in lv50 quests an AoE is really powerful, and they eventually will even get more aggro than you or they won't heal you in time and you'll die. So please, avoid aoes. It's easy and doubles (at least) the probabilities of success.
- Don't stay too far away from healers. I know, this is hard to do, you have to keep mobs away from healers, but the best way to survive is not to run away, because healers won't reach you. Just stay as far as you can by remaining in healers' range. But this is not so important, a good healer will get as far as he needs by himself.
- Make sure you avoid any unnecessary damage, by increasing defence, avoiding aoes and such, because getting too much damage = being healed more than you should = less MP and more aggro on the healer(s).