What Jokester said. The enchanter crafted wands are great at low level. I shield, smite, SWPain and wand to death. Rinse and repeat. When you get fear use that as get out of jail. Alternate points in Spirit tap and wand specialisation. Then two in improved SWPain and three in Shadow focus. There are guides after that, I can't remember where they go next. Don't just use the max rank of spells. Sometimes lvl 1 will do the job.
Shield plus inner fire will mitigate most damage. Wand plus talents is the key.
I'd suggest your first 5 points in Spirit tap, with a greater magic wand (you do more than enough damage), then once you're 5/5 put 2 into improved SWP (reason being is that if you pull 2, you'll want to drop SWP on both and the secondary mob will take more damage from the increased duration) and 3 into Shadow focus. Then at 20 get Mind flay, then move over to get wand talen. As at that point, wands damage starts to tail off so you'll see the most benefit then.
As for rotation, at that level, it should be MB > SW : P > PW:S > Wand, maybe throw in a Smite before MB if you fancy killing a bit quicker, with the spirit talent, you should never be OOM or even close. Always full. If you pull more than a couple, you have a full mana pool to use.
Once you have mind flay at 20, drop Smite, it's not efficient. Use mind flay to sap away running enemies. My rotation hasn't failed yet and I doubt it will anytime soon. However I know others prefer to open with SW : P simply for the extra tick or 2. But the con is the mob gets to you before you're done casting so you'll need to have put up shield first, which if you pull 2, it may drop sooner rather than later which is never a good thing.
Buffs, always use Inner Fire and PW:F, kind of a given, if playing a undead priest, Touch of Weakness is always nice to cast after looting a mob as it's low cost yet helps lower damage should your shield go.
