i always focus on killing the weak/standard mobs first then move on to silvers then golds. Normaly i use a tank with a pull. Either Assassin or Powertech. So i rush the group with the closest mobs. so if 5 mobs total 3----2 I rush the 3 pack pull 1 of the 2 pack and taunt the 2nd of the 2 pack. Have my dps kill the lonely weak mob by him self first then kill the mob group im tanking.