For leveling, just using cooldowns is fine. I rarely use Concecration, however, unless I am in an instance group, or pull more than 2 mobs.

Usual rotation is Judge (Wisdom), Crusader Strike, Divine Storm, Exorcism (or pull with this if at range). When they get below 30%, smack em with the Hammer of Rigieousness.

Always use Ret Aura, Blessing of Might, and Seal of Command.

Try and pull only one mob at a time, unless they are green, then 2-3 is safe.

Bubble and Holy Light as needed, or Lay on Hands if in dire strights.

- Sang