I'm surprised how many people don't know their shit... some of you people actually play priests?
Don't macro Inner Focus to your spells. Dumb idea.. Use it smart.
Flash for emergencies. It eats mana, but heals nice.
Penance and PoM on cooldown.
Use inner will. Its nice :3
Int > Haste > Mastery > Spirit crit is the worst stat
The key to disc is PREVENTING damage, not healing it. With grid you can see who has agro, so putting shield on them before they take damage will be better.
More raid-situational, but use binding heal to heal your group (especially if you're about to take damage)
Also if people stand in dumb shit, fail shit (interupting is hard), and suck (like what happens in 99% of pugs). It WILL make your life a living hell.. because people dying to fire will always blame the healer before they learn how to play.
tldr; holy <3