I don't think I've made a TL;DR post for this yet.
Myself and Waterdrop have been making raid videos for guild boss kills. I pay close attention to those videos not just because of Waterdrop's awesome music selection, but because I learn a lot from being able to see what he sees and *what he chooses* to see.
Most raiders have their own UI setup. They usually have a boss timer addon (like DBM) that places timer bars and alerts on their screen somewhere. A good number of people (not just healers) have raid frames on their screen so that raid health/debuffs/aggro are visible. People usually have their important cooldowns/abilities on hotbars somewhere on their screen -- not necessarily so that they can click them (since many are keyboard bound), but so that they can track the cooldowns on those abilities. Lots of data on the screen. Just because the data is there doesn't mean that people are necessarily paying attention to it.
There are two key pieces of data that people have to *actively* choose to see. The first is your /focus target. When you /focus a target, it causes a frame to appear on your UI somewhere so that you can see information about that /focus target. You may say, "Well, my own UI has boss target frames already; the focus frame is redundant." That's fine, but how often during a fight does your eye wander over to the boss frames on your screen? How distracting is that visual loop? By using a /focus target, you can *establish a mental checklist* for yourself to use during a boss fight. I'll use normal mode Shannox as an example. Let's say you're ranged DPS. You're attacking Riplimb. You get Riplimb down to 10% health. If you have a /focus on Shannox, you can *remember* to check that his health is around 35%. If you don't have a /focus on Shannox, you now have to pan your camera around, target Shannox, read off that his health is 50%, and decide to change targets. The /focus is useful for tracking things that you want to know -- if I'm tanking heroic Shannox, I *want to know* when Rageface is in an ice trap so that I know to reposition the raid. The easy way to do this is /focus Rageface and check his debuff icons periodically.
This segways into the second key piece of data that you have to actively choose to see -- your camera viewing area. By default, the camera points in the direction you're facing. Do the following exercise. Go to a target dummy. Rest your keyboard hand on your 1234 (or wherever your DPS hotkeys are) and start doing your rotation. With your mouse hand, left click on the screen background and drag your camera viewing area around *while you continue to DPS*. Notice that your DPS doesn't stop (it can get a little sloppy, but at least it isn't zero) while you are able to look around you.
http://www.youtube.com/watch?v=W-2saVLo ... 1#t=03m26s
In this video, I am tanking with this humongous dragon obscuring my view. I also agree that my UI has tons of crap all over the screen. Note that despite all of that, I am actively panning my camera to determine where the other dragon is going to strafe nuke the room. My rotation may have gotten a little sloppy (do a two holy power SotR or munch the holy power generated by a fourth crusader strike), but *my mental checklist* told me to prioritize attention to where the strafing dragon is and downgrade my rotation to secondary or tertiary status.
Here's another exercise that I highly recommend doing. Go to the 'Game Menu', hit 'Interface', go to the 'Game' tab, and select the 'Camera' line. There should be an option for 'Camera Following Style'. I highly recommend setting this option to 'Never adjust camera'. Why? Do the following. Use your mouse hand and right click to point yourself in a direction. Let go of the right mouse button and then hit the 'W' key on your keyboard to start running forward. While running forward, use your mouse hand to left click on the screen background and drag your camera viewing area around *while you continue running forward*. Notice how you keep running forward on your original vector (determined by where you right mouse click dragged), but can freely view while left mouse click dragging. Now pan the camera with left mouse click so that it is 90 degrees to your right. Now immediately hold right click and 'barely' move the mouse -- you immediately make a hard right turn. You can even use this trick to turn 180 degrees on a dime. Why is this important?
Lots of boss fights have movement phases. By using left mouse button camera panning and right mouse button snap direction changing, you can *segment* your movement phases. For example, I can right mouse button drag to set my initial movement vector and then start moving forward. While moving forward, I can use two instant DPS abilities. During the 1.5 second GCD of one of those abilities, I can left mouse button pan to *reassess* the area and perhaps select a different target (e.g., hanging spinners on Beth'tilac) or use a right mouse button drag to alter my direction vector. Alternatively, you can push all of your movement over to your mouse hand by holding the left and right mouse buttons at the same time to move forward. You can then drag the mouse to change your direction while you use your keyboard hand to hit hotkeys for instant abilities.
The camera trick is probably even more important for tanks. If you are using the 'S' key to slowly move backward, you can use your left mouse button to pan your camera to look around the boss' huge hitbox (e.g., identify where Rageface is trapped on heroic Shannox) or look behind you (e.g., so you don't walk into a flamethrower on Alysrazor).
So now that we have all this data...boss addon timer bars, raid frames, our camera viewing area, our /focus frame, cooldown timers over our hotbar abilities...so what? Isn't the raid leader going to call out on vent if I'm standing on an immolation trap or when to move? *Any time* that you wait for someone on vent to call something out, you are acting 1-2 seconds later than normal people would. Why? Look up -- there's this big TL;DR post about data on your raid leader's GUI that he has to see, recognize, mentally think of an action *not for himself to do, but for you to do*, and call that action out over vent. You then have to hear this over vent, realize it's directed at you, and act.
This leads to the last item which is preparation. *Whenever you are surprised* by something in the raid, the sensation of surprisal is due to not being prepared. Most raid boss fights are highly scripted. Some major actions happen on a timer -- boss addon timers take the surprise out of these. Some major actions are telegraphed -- panning your camera to see the lava wave coming from Ragnaros' hammer takes the surprise out of these. Some major actions build up progressively -- /focusing a target to check its buff stack or watch his energy bar takes the surprise out of these. Notice the pattern? Any time something surprises you in a raid, determine if you have a UI element that will take the surprise out of it on the next pull and *add it to your mental checklist*.
One item that people usually don't categorize as a surprise (but actually is a surprise) are their cooldowns. Lots of player classes have overpowered abilities; since they're overpowered, Blizzard gave them cooldowns. During the course of a fight, if you run into a situation where you want to use an ability, but it's on cooldown, *make a mental note of it*! Think about what it would take to ensure that ability is not on cooldown at that moment in the fight the next time you pull the boss. I've made another TL;DR post about personal strategy; this fits in with that topic. For DPS, there are two great times to use damage boosting cooldowns: during any time the boss takes bonus damage (e.g., phase 3 Alysrazor) and during heroism. You may say, "My DPS trinket has a 2 minute cooldown, but it's really hard to determine when it's 2 minutes before a boss damage phase.". Then don't base it on a timer -- base it on something else. If a boss fight has scripted add spawns, make a mental note to not use your trinket after the fourth add has spawned. If a boss fight triggers phases based on boss health, make a mental note to not use your trinket once the boss passes 15% health above the phase transition threshold. There are very creative ways to *prepare* to do good DPS.
This also applies to healers and tanks. Using Majordomo as an example, a lot of good healing and tank abilities have 3 minute cooldowns. If you find yourself clustering all of your abilities on the first scorpion phase, then find you have no abilities available during the second scorpion phase (which has seeds), then make a mental note to alternate your abilities between odd and even phases on the next attempt. Even short cooldown abilities like HW:Sanctuary; if you use it on cleave #3, but it is on cooldown for cleave #5 when you really need it more, then make a mental note to time it differently on the next attempt.
Remember that these timings can change. When I tanked Ragnaros pre-nerf, I would use my divine guardian to mitigate damage on my partner tank for the first magma trap detonation. My preparation told me that the divine guardian would come off cooldown just in time for the first molten seed detonation in phase 2. After the nerf, the raid pushes phase 2 earlier and my divine guardian would come off cooldown in time for the second molten seed detonation. Just because the timings can change doesn't mean you should ignore planning your cooldowns.
Remember, if your raid wants a 90% chance to kill a boss, each of the individual 10 raid members needs to perform at 98.95% chance of not making a fatal error (0.9895^10 = 0.9). Make sure that your UI and vent dependency are not the reason you are failing.
-HP
