One thing that has helped me is occasionally playing a toon solo in a 5-man or raid and using the same 'button mashing" macros/etc that you use when boxing, but paying close attention to everything, in case one of the macro seems to be getting hung up on a cooldown or a typo in the macro.

Of course, it's also very helpful to read up on your class/spec on places like ElitistJerks (as others have suggested) to figure out your ideal spell rotations, talent specs, glyphs and stat weights.
For what it's worth, I've had to tweak some of the 2-step macros that Mercurio posted, to keep up with my gear progression and play style. The macros are a good place to start, but don't take them as gospel. Feel free to tweak them to see if you can get better DPS.