Being the Dragon is no different than when you are fighting in human form. Sometimes you have to duck and run and then come back. That works especially well in the flying fortess parts.
Make sure you invest points in Dragon Spirit so that you can heal yourself up with out using potions. ALso, If you are getting low on hitpoints you can transorm back to human form and the Wyverns and ballistas do not attack you. Sometimes that's the best way to heal yourself back up again.
