We all have that night. Whether it's your trial run with a new guild, or you're a veteran raider, there's that night where you're just making mistakes. And it's really embarrassing. Here's some common and mortifying mistakes and how you can fix them.
Standing in Fire (or void zone, or other thing you shouldn't be standing in): This can be really embarrassing - I mean, Blizzard even made it a loading screen tip! But everyone does it once in awhile. The big question is WHY did you stand in the fire?
Did you tunnel vision? Make sure your not just focusing on your own rotation and dps - a dead dps does 0 dps.
Can you not see it? You might need to turn up your settings a bit, or turn on projected textures. Maybe you have an addon blocking your character's feet. Play around with it.
Are you lagging? Try clearing an addon's cache, or turning them off entirely. I know things like Cellular, Recount, and Gatherer will dramatically decrease your performance if you haven't cleared them recently, or have them on for raiding. If it's not your addons, check to make sure your computer isn't running a virus scan or update. You can also try rebooting your router. And make sure your roommate isn't downloading porn during raidtime.
Not running out when you get a debuff on you: This can lead to more than your death, depending on the debuff. Think things like "Swarming Shadows" from the Blood Queen Lana'thel fight, or "Lightning Conductor" from Electron on the Onmotron Defense System. Standing near others while you have these debuffs causes extra raid damage to go out, putting more stress on your healers and potentially killing more raid members. So what happened?
Did you not see the debuff? Make sure your debuff bar isn't covered. Enlarge it or move it so you can pay better attention to it. Make sure your boss mods are announcing when you get a certain debuff.
Did you tunnel vision? See above.
Dpsing the wrong target: This can really hurt your raid's chances if your doing it on a fight like Omnotron Defense System or the Ascendant Council.
Do you not realize that you're on the wrong one until it's too late? Make sure you can see your target frame very well and it lists the name of your target. You can try enlarging it or moving it.
Did you not hear the call to switch? If you're playing music or have a TV on, turn them off. You raid leader low? Turn him up or ask him to talk a bit louder. If you're getting distracted easily, try clearing everything off your desk and removing other distractions from the room.
Did you tunnel vision again? See above.
Missing interrupts and killing the tank/etc: Arcanotron packs a nasty punch with his arcane blasts, and Halfus with his shadow nova. Why did you miss the interrupt?
Did you not even cast it until it was too late? Check your latency. If you're a bit laggy, ask to have someone else take over interrupts. Make sure your target's cast bar is big enough to see and not covered by anything. If the target is casting too fast to interrupt, make sure they don't have a buff that's causing it. Have a mage spellsteal or a shaman purge if this is the case.
Was your interrupt on cooldown? Coordinate with other interrupters so you don't all blow your interrupt on the same spell.
Did you cast at the right time but your interrupt missed? Get hit capped! I know shamans need to be spell hit-capped (17%) for theirs to hit 100% of the time. Depending on your class, yours maybe different.
Tunnel visioning? See above.
Starting to dps before the tank has proper threat, pulling aggro and killing yourself/others: This is especially bad if the boss has a cleave or cone breath attack. You always want to make sure the tank has the mob in position and a decent threat lead before you go all out.
Did you blow all your cooldowns right away and pull aggro? Jumping to the top of the dps meters right at the beginning of the fight doesn't matter. Don't pop your cooldowns right away, give the tank a good 10-15 seconds.
Did you pull threat on a trash mob and die? Ask the tank or raid leader to continually mark or call out kill targets. Consistently marking a skull will help make the trash go down smoother since everyone will be focusing on the same target.
Your dps just really sucks: Nobody likes coming in on the bottom of the damage meters. If your dps is especially lackluster, try to figure out why.
Are you using the wrong rotation? If you have a raid mate that's the same class and spec as you, ask them about their rotation. You might be doing it completely wrong. Try out different combinations on the test dummies until you find something that works for you.
Are you reforging/gemming/enchanting wrong? Look up guides on sites like ElitistJerks.com Make sure you're getting hit capped (and expertise capped for melee).
Is the fight really not optimal for you? Some fights just aren't good for certain classes. Movement fights suck for melee. Stand-there-and-hit-it fights are awesome for melee! If you only really suck on one or two fights, this is more likely the problem than bad gear or poor skill.
Not knowing the fight at all: If you don't know the fight, you're much more likely to die to something silly, or make a mistake that causes a wipe.
Have you never seen the fight before? We've all been here and it's okay. Prepare as much as you can by asking your raid leader which fights they plan on doing. Watch videos and read strategies about the fights.
Did you not listen to the explanations? Get rid of unnecessary distractions, turn off music or TV, turn up your raid leader.
Sometimes you just end up having an off-night where you're making a lot of silly mistakes. If this happens. suck it up and ask to get replaced. Your raid leader will respect you for that. Take a bit of a break, watch a good movie or read a good book. Have a relaxing bath or shower and a bowl of ice cream. You'll feel a lot better and be ready to tackle the next raiding night.