"Read the strat!" It's in every raiding guild's Guild Message of the Day at some point. There's nothing more annoying to raid leaders than to have one person wipe the group because "I didn't know the boss was going to do that." But there are different ways to prepare for a boss fight.
When I'm told to read the strat, I usually head over to WoWWiki for a basic overview of the phases and abilities, and then to Bosskillers to figure out what I actually need to do as a rogue (or, on some fights, whether I should actually show up.) A lot of people swear by video strategies, as they can offer an unparalleled view of what the actual fight is like, but I never liked them that much. With everyone else's addons and stuff clogging up the screen, plus the myriad of different perspectives, it can be tough to figure out what the boss is actually doing. One guild I know used the somewhat unusual strategy of getting people from the opposite faction who had killed the boss they were working on to come into their Vent during the raid and talk them through it.
When you have to "read the strat", where do you go? What do you think is the best method to learn a new boss fight?