Honestly, the biggest tip is that your group understands the strategy.
1) Casters stay as far away to get the least amount of de-buff (Healing time increases the closer you get). If you get sucked in (boss special ability), turn around and run back to your original position ASAP. Do not try to cast a heal while you are there (unless it is an instant one).
2) Position yourselves in a triangle. Tank & melee at one point. You at the other. Ranged DPS at 3rd point. Make sure you are at max distance from each other.
2a) If you get "targeted", run to ranged DPS point to avoid more damage.
2b) If tank or melee gets "targeted", they should run to you to avoid damage.
2c) If ranged DPS get "targeted", they should run to you to avoid damage.
The key is to get out of the flare ASAP. If anyone gets hit with it and stands there, they will die. You don't even want to try and keep healing through that...
Finally - follow Twirdman's advice.
Edited, Jun 10th 2008 8:50am by YJMark