WoW newbie looking for advice

[Frag]

SW:P first, always, always, always, always. The only time that this is over ruled by is when you get Vampiric Touch at level 50. DoTs always go up first for a Shadow Priest.

Here's how you pull as a Shadow Priest as a sub 50 shadow Priest:
Cast SW:P while backing up, cast Vampiric Embrace while backing up, cast Power Word: Shield while still backing, when global cooldown finishes, cast Mindblast, cast Mind Flay, then cast Mindblast and Mind Flay and use wand while reapplying Shadow Word: Pain and Power Word: Shield as needed.

Inefficient.

Max range: Mind Blast >strafe > SW:P while strafing> Mind Flay>Mind Flay> Wand.

There's no need to waste mana on vampiric embrace as they're not going to damage you overmuch anyway providing you're grinding on the proper mobs and quests. As for PW:S, since there's little reason to cast with a mob in melee given the -hp% that the alpha strike provides and the dps of SW:P on the mob means that the mob isn't going to be in your face that long, so uninterruptability isn't of great value. Past 50 substitute the opening MB for VT. Now, if you're working on +1-+4 quests/mobs, instead of efficiently grinding out green, then heavier mana usage rotations per mob might be called for. Either way, if you have room to strafe, use that to gain range instead of backing up, will typically allow for a half to most of a full Mind Flay with just that change.

Cheers,
~Frag