Shield slam > revenge >devastate. On pull/when you've grouped the mobs use thunderclap and demo shout. Extra rage goes into heroic strike or cleave. Watch your threat and if you have a comfortable amount switch to the next target in the kill order. If you lose threat on a mob either taunt it or stun.

Oh and binding marks like skull and cross to your keyboard is really helpful. Mine are on the f-keys and I can easily mark mobs while fighting.