5/5 Cruelty is perfect for starters. For leveling, I'd next go 3/3 Imp Heroic Strike (being your main damaging ability for a long time), then 2/5 Deflection to get to the next tier, then 2/2 Imp Charge, then finish off Deflection, then 2/2 Imp Overpower, 3/3 Deep Wounds, and 2/2 Impale. By then, you should have a good idea of where you want to go. At 40 you'll want to respec either 31 Arms or 31 Fury for Mortal Strike or Bloodthirst respectively.