The guide we have was written for Patch 3.3, it is pretty dated.
A bit of fast and flawed advice to get you started:
Hit (until you hit 446, the cap) > Int > Haste > Crit > Mastery
Because of talents, you don't have to gear for hit. All of it comes from Spirit. So take gear with +Spirit on it, NOT Hit.
For spells, we use a priority system, not a set in stone rotation.
(If below 25%) Shadow Word: Death > DoTs > Shadowfiend > Mind Blast > Mind Flay
This basically means you should keep up DoTs, keep Mind Blast and Shadowfiend on cooldown, and mind flay when you have nothing else to do. If this is too much, just remember "ABC: Always Be Casting".
Here is the generally accepted cookie cutter spec. You can drop the remaining two points anywhere you like. For PvE and the occasional PvP I like to put them in Phantasm.
This is what is most likely the cookie cutter spec at 85. Major and Minor glyphs can be anything.
That's pretty much it, off the top of my head. I'll edit in anything I forgot later.
Edited, Nov 20th 2010 6:13pm by IDrownFish Edited, Nov 20th 2010 6:14pm by IDrownFish