Spriest use

In Pve I found myself falling behind bc of my Mana running out. I have a 71 spriest. I dont really remember running with a spriest,with my alts, so i really dont know how to use them in an instance. What I am looking for is what is the best or should i say most efficient way to use a spriest in pve. Also I want a new way to set up my interface so that i can effectively off heal if ness. I have three buttons on my mouse that i can use for casting spells too. I also play in a pvp realm so i got to keep everything the same for the most part. I dont want to be switchin spells around or i will never feel comfortable. I know this is a long thread, but for any pro Spriest I would appreciate your input.

I used to have the same problem with my Shadow Priest. Until I started utilizing my Shadow Fiend more. And Dispersion helps out soo much. If you start to use those you will run out of mana WAYYY less. Hoe this helps. I am not sure id you have Dispersion yet. is is the last talent in the shadow tree.