Those who are getting ready to start PVE raiding or have started or are having a difficult time keeping up, this guide is applies to all classes and roles in the game.
   You know in a raid, effective play is doing whatever is needed to make the raid successful. There are three raiding roles available which have desirable traits players are trying to adopt. There are things like that quick reaction speed, strong output and aggro management.
Here are some key virtues of top raiders. Let us get started.
The first one is critical thought. It is able to look at something with the intent of improving it. Good Warcraft players must possess this skill. Improving play has to be a rational process, not an emotional one. Before somebody tells you that you need to step it up, you should already know that you need to step it up, and be thinking about how. Understand there is always room for improvement, even in the best players in the world. There is no such thing as good enough.
Likewise, you should look critically at advice you receive. It is better for you not to listen to the first thing someone tells you because the advice is not good all the way. Take it under advice, compare and contrast it to other sources, and derive your own conclusion. Even guides should be subject to critical thought, though you can read up on their class. Don't accept anything as gospel unless that source has proven to be reliable after time.
Questing is forgiving. You can do whatever you want and you'll hit endgame, even if it takes half a year. Raids, even the easy Wrath of the Lich King raids require you start to understand that there are more effective ways to play than others. You can't just make stuff up anymore. Luckily, those who understand the mechanics of the game, and churn out the numbers regular players can use to improve their game.
Most commonly, players just don't know how to crank up their output for raids and the answer is invariably using the most popular setup. If you're willing to accept you will have to work harder, and likely won't succeed at matching the output of the optimal setups, you can start playing with non-standard stuff that may be more to your tastes. Read the information, understand it and go from there. As always, employ critical thought. If all the guides say the same thing, chances are the information is tried and true, but feel free to examine it more closely. If you're thinking, you're improving.
Attitude is a constant struggle. Almost all raid leaders want the same kind of attitude from players, and there's always a few people who refuse to play along. Here are some signs of a good raiding attitude, and how to adopt it. For example:
Don't use the meters as a form of competition. Damage meters are a very useful tool, but they're not to be waved around in the middle of a raid, save them for after.
Be a mentor. If you're doing well, start sharing your information. Give the struggling raiders the tools they need in order to succeed. It's a team, and the team will advance farther if everyone is helping out.
If it is a sideways upgrade, pass on loot which wins you instant friends and lets somebody who might see the drop as a major upgrade make enormous improvements. If distribution amongst regular raiders is even, the raid improves overall.