There is a lot of inertia involved in starting a priest from scratch.  You have this thimble-sized pool of mana and a tiny little fly swatter of holy damage with which to flail your enemies into oblivion (feel my holy wrath, insect!  only twenty more swats and you’ll be dead!).

I exaggerate only a little.  You actually have at least three fly swatters, only one of which is holy, but it’s the only one that won’t make the fly roll on the floor laughing at you.  I refer, of course, to Smite .  But Smite carries a relatively large mana cost at this level, so you need to smite judiciously.  As the Templars of old once said, smite often, but smite wisely.  Part of this can be mitigated with the aforementioned wand, but what else can you do to minimize the time that you stare at your motionless toon, sitting cross-legged on the gound, drinking water?  (i.e. times when even they look bored)

You either use less mana to slay each beast or you stretch that thimble until you have a full tablespoon.  Of course, you can also  sacrifice your body and take a few whacks while you’re wanding them down (you’re a healer, suck it up).  Fortunately, thimble-stretching and improved body-whacking are within your grasp.  You can actually improve your stats relatively cheaply at this level by becoming a tailor!  Running around Tirisfal Glades and Silverpine Forest, you’re going to hit a lot of things that drop linen.  Use it.  You can be decked out in greens before you hit level 13!

My warriors and paladins were always blacksmiths for similar reasons, and while it’s hard to visualize my unholy Forsaken priest cackling with diabolical laughter while executing a Herringbone Stitch, it’s hard to argue with the results.

Finally, my fellow true believers, you should look into maximizing your bang for your buck.  What are the three most important secrets to maximizing your damage per mana point?  As my realtor would say: rotation, rotation, rotation.  …or do they say something else?  Anyway, when you are fresh out of Sunday school you pretty much have only Smite to work with and your non-effective fumbling with a melee weapon.  But now that you’re, say, at mighty 13th level, you have a few options.

Here’s what I’m using now (half-way through 13th level): Power word: shield, Shadow word: pain, Mind Blast, Smite, Smite, and wand, baby, wand.

I find I can get through at least 3-4 mobs this way without drinking.  You’re mileage may vary.