I will start researching it a little more, but I am still working out the right healing-spell rotation on the Priest.
I always keep a Renew up on the tank during a fight, I heal him back up with max rank Greater Heals or smaller heals if they suffice. I think I usually find myself spamming Renew – max GH – max or less than max GH – Renew, repeat. I never use Flash Heals, I do think reading somewhere that they are very mana inefficient. Sometimes I throw a Shield on the tank. If multiple members take damage, I throw a Shield on the most damaged and hit him with a Renew while I keep focusing on the tank.
I just respecced her to Circle of Healing. I find it fairly useless unless I spam it if the group takes damage; I also see myself tempted to blow a Prayer of Healing to get them back up faster (extremely expensive though, almost 900 mana).
If tank and I take damage, I may use a Binding Heal, which is also somewhat expensive as well however.
I guess I really have to do some more research. 🙂