First Things First

Bandaging.
You should have 375 FA and have at least 20 Heavy Netherweave bandages on you for raid. You should be looking to bandage yourself any time you take damage first before expecting a heal. This is to ease the aggro and mana for the healers so they can concentrate on the tanks.

Do not battle loot.
It means your head really isn’t in the fight, you are distracted, you aren’t killing/tanking/healing when you need to be.

Don’t constantly talk about what drops you want.
Everyone needs some type of upgrade, but we have to be fair to everyone and we want to gear all members as best we can so we can progress as a group. Make a list and keep it to yourself unless someone asks you. Don’t be greedy, if you get something, and something else drops that is an upgrade to you and someone else, share the wealth since that person is dedicating their time to help you as well.