The people above gave great rotations, so I don't have much to offer there.

The only thing I wanted to mention is better gear and marking targets. You should never be more than 10 levels below in gear pre-50, and try to always gear up big time after 50. A lot of people don't understand how important gear stats are for holding enmity (and taking hits). It might be worth even taking several STR accessories in place of VIT to deal more damage.

As far as marking targets, that's pretty simple. You can place number indicators over mobs (I do this every trash pull in dungeons), so your team knows what to target, and in what order. This should ease the pain of DPS all attacking different targets significantly. Beyond that, the combos listed above are pretty solid.