For healing, I use the Function keys F1-F10. F1-F5 tells my Priest to heal party members 1-5, F6-F10 tells my Shaman to heal party members 1-5. It has worked out very well for me.

I usually have my Priest cast renew on the tank every time he casts Holy Shield as well. I've used different tactics here (Renew when casting Consecration, Judgment, etc.) so I'm still getting used to this better.