Raiding 101

[Parasprite]

Raiding is hard.  Playing your class to your fullest potential makes raiding easier.  The following should be required for raiding.

Step 1: Mastering your Class: Talents, Glyphs, and Rotation
Elitist Jerks
I can not stress how important it is to read your class & specs thread on this website.  Whether you are a tank, healer, or DPS this is a must.  Picking the right talents and glyphs, and using the right abilities at the right time for single target and Area-of-Effect situations is a tremendous benefit to the raid.  Elitist Jerks is highly accurate because it is constantly peer reviewed by people downing the hardest content in the game.  Even if you think you know everything about your class, there is always something that can be learned and Elitist Jerks is one of the best places to learn it.

Step 2: Gearing Part II: Gems, Enchants, and Reforges
Gear Optimizer
So you've done 1,000 Heroic Dungeons and are looking purple.  Item Level isn't everything though, and you can squeeze more out of your gear by picking a better set of gems, enchants, and reforges to make it truly Epic.  The site linked is a good calculator for Reforges, and has editable stat weights.  Once again, Elitist Jerks also has very good suggestions on what gems and enchants are good for your class and spec.

Step 3: Consumables: Flasks, Food, and Potions
There are three categories of consumable items, all of which are equally important in downing bosses.
Flasks increase your primary stat by 300 for one hour and persist through death.
Food increases your primary stat and stamina by 90 for one hour, but death ends them so it is important to eat before every boss attempt.
Potions are items which are used during combat to provide a short but very large boost to stats, examples are Potion of the Tol'vir, Volcanic Potion, Golemsblood Potion.  These are good to line up with strong cooldowns like Time Warp and also help tremendously with the end-phases of many fights, where there is a small amount of time to kill the boss.

Step 4: Fight Knowledge
For some fights there are 10 different players with 10 different jobs.  It helps if you read the Dungeon Journal or watch the fight video beforehand, so that less needs to be explained during Raid.

[Sweetiebear]

This needs to be stickied. Now.

While I'm not even max level on this toon, I have WotLK raiding experience, and know just how idiotic some ponies can get.

Example? I was once running FoS and PoS 5-mans to help old guildies gear up, and being a tank was the easy way to do it. I managed to grab one of our higher-geared holy pallies who was online to heal so the DPS didn't have much to worry about. Turns out the pally was wearing cloth armour.

I can personally not stress the first point enough, if you do not know your class, learn it. If you do not want to learn, then that's fine, just don't expect that there will be a lot for you to do. While it is a game, it can get fairly complex at points, and knowing yourself and how you work is one of your best defences. That's why I mainly play druids, I know how they work well enough that I can apply it when needed, or help others who are learning.

Just my two cents, and Para, your main post already says everything need to be said, I just wanted to add my experience with learning how to raid, lol.