Taken from MMO-Champion forums.
This is my own comprehensive take on tips and tricks you should get used to before Cataclysm hits, for tanks, dps, and healers. Some of you may very well know these things, even if you have only played during Wrath. However, some of you may have never needed to use or think about them. Everyone has the potential to improve. I have things I need to improve on too, some of which are things I discuss here! I don’t think you suck personally, but I do think that we’ve ALL gotten complacent and rusty with Wrath of the Lich King. Players who started playing in Wrath never got the experience of Classic and BC where we once had to learn many of the lessons that will be invaluable come December 7th. It’s not their fault, but it needs to be addressed.
1.) Be mindful of your positioning. Do these mobs have a knockback? Will you get thrown into other mobs? Is the tank facing the mob away from the group in case it has a conal or cleave? When trying to dodge that fire on the ground, are you running towards another group of mobs? These are things that you will need to be more mindful of in Cata. Extra pulls can and likely will mean wipes, and any damage that can be avoided will make your healer’s life that much easier, and make their mana last that much longer.
1.a) If you do get aggro, run the offending mob TO your tank, not AWAY from him. Root or snare the mob that is aggroed on to you, and then move TO your tank so that the mob will run closer to them as well. This makes it much easier for your tank to peel the mob off of you, and will get you back into safety quicker.
2.) Communicate with your group. It doesn’t matter if you’ve never seen these people before in your life. Ask who you should CC. Ask the tank to pop his CDs because you know you have trouble healing this pull. Ask if you have questions about an encounter (please, for god’s sake). Ask for a mana break. Don’t sit there like a deaf mute along for the ride and pray everyone else knows what they’re doing. Much of the Cataclysm content WILL take some organization.
2.a.) Take and give constructive criticism. If you wipe, try to figure out what went wrong and fix it without liberal use of “suck,” “noob,” “fail,” “ragequit,” etc. That will not get you any closer to downing the boss or the trash. It will only destroy any cohesion your group had, and angry players tend to perform worse than calm or happy players. Also, if someone else offers you criticism, don’t take it too personally.
3.) Keep your group’s best interests in mind. Pay attention to what is happening to your group members. Is a mob running for your healer or clothies? Root it, slow it, or stun it. Did you get an extra add? Try to help control them- slow, CC, etc.
4.) Be patient! This is all new content, and your group is in leveling gear, not top-tier epics. These fights are not generally easy, and have some new mechanics to learn. If someone in the group needs to have the fight explained to them, don’t complain. If your groups wipes, run back in and try again. I’m sure you had to learn the fight at some point too. If the healer needs to stop for a mana break, don’t keep pulling or get impatient. Trust me, they are working hard to keep your group alive. DON’T expect 15-20 minute runs!
5.) Be observant. Check out new buffs, debuffs, and spell effects. The more you know about what is around you and what mobs can do, the more effective you can be. Mages in particular, watch for TASTY Spellsteal fodder. You’ll be amazed at the buffs you can give yourself and take off of a foe.
6.) Consumables!! Yes, that’s right! Health potions, mana potions, potions of speed! Well, mostly health and mana. Have them! Use them liberally if you have access to them! Mana potions in particular can give healers the extra mileage they need on a tough fight.