Play well. Get tons of commendations even on dps. Can quite frequently come out of expert with 1 or 2 on my samurai just because I know how to aoe and use bloodbath to cover any splash damage I take...

It really doesn't take much to rack up commendations. People often say the tank and healer get more. As dps is less noticable. But when your at the final boss several minutes faster than usual its noticable...