I recently got my priest restored who I leveled as Shadow and I've since gone Disc on her in order to level up through dungeons and healing. Back in Vanilla days when I was last healing on a Priest I was shielding, and using renew as my heal over time, making sure it's on the tank all the time etc.
My experience today has been mainly shield the tank and throw a penance when he needs healing. Do disc priests not have a heal over time effect? or am I just making sure my shield is on the tank at all times?