A few tips that could help you maintain emnity over the healer. Above all less damage means less healing. Avoid aoe. In the lower levels this will be a red zone. In higher levels you will learn to watch the cast bar. Turn the mobs away from the casters. If they are getting hit due to positioning this will cause more healer aggro. If you need to move to avoid aoe immediately move back into your original position. Position all mobs in front of you. You cannot parry single target hits from behind or the sides and will take more damage.