- Get a wand.
At low levels priest damage is really bad and mana regen sucks. That's why having a wand to help finish off mobs and start mana regen ealier really helps. - Spec for SpiritTap
Spirit Tap is the most important leveling talent for priests. It must be your first talent you take becasue it allows you to waste less time on drinking. - Avoid shielding
Shileds are awesom, but they consume a LOT of mana. I would advise picking up inp. renew and use renews early on in the fight instead of P.W Shield. - Spec for Shadow
In case it was'nt obvious- spec into shadow to kill stuff faster and level faster
- L2Fear wisely
A lot of players do the mistake of using fear only as a last resort before dying. That's a mistake because fearcan be a powerful grinding tool, and can be used to greatly increase leveling, also if you use it when you're close to death you'd probably just endup fear-pulling another mob and die anyway.
DoT a mob and then fear+ Mind flay him. This will prevent most fear- pulls, and make sure you're not heavily damaged and ready to progress to the next mob (he will probably die while feared or short after.
And those were my 5 tips for leveling a priest!
Add more if you want.
Tiipper.