So you want to level a warlock but aren't sure how you should start? Well, look no further, as this newbie warlock guide will tell you everything you need to know to be running around cursing everything in no time. We'll discuss race choices, what kind of gear you should look for, and the basics of warlock DPS.
The first thing you're going to want to decide on is your race. If you already have a race you like the look of, just go ahead and choose that, as racial abilities aren't that big a deal in the long run. That said, human and undead are the two best races for Player versus Player combat, and gnome and orc are the best raiding races. Pick whatever you like, though, as it really doesn't matter anywhere near as much as player skill, gear, and other things.
Next lets talk about gear. It can be confusing figuring out what you should gear for as a newbie of any class, and warlock is no exception. In general, though, while leveling you should aim for the following:
Enough hit rating to have ~4% increased hit chance so you don't miss (it takes more the higher your level is)
Spellpower and Shadow Damage
Spirit, Crit Rating, and Haste Rating
If you have to decide, Spell Power, Shadow Damage, and Hit are all worth about the same, and the rest is worth about half that per point. You'll notice I didn't mention Stamina or Int; these stats are both pretty subpar; your pet will be taking damage, not you, and Int isn't very good for Warlocks compared to other stats (it's worth maybe a tenth of what Spell Power is worth, per point).
So now you're geared and ready, so how do you play exactly? Warlock is pretty simple. You basically want to just toss your DoTs on the enemy and let you pet tank. The first levels can be rough because you don't have a pet, but things get easy as soon as you get one. At low levels, you want to generally use Immolate, then Curse of Agony, then Corruption. Then you can just wand the enemy down (speaking of which, buy a wand as soon as possible!). Between your pet and these spells, the enemy should die very fast!
A few last tips: Don't use Fear except in emergencies; all to often you'll pull extra enemies as the monster runs around. Be patient; don't burn all your mana spamming Shadowbolt, it's quicker to wait and let your dots work so you don't have to drink so often. Always carry food and water, so you can recover quickly from nasty fights. Sell EVERYTHING that is white quality or better on the Auction House; this will provide you with enough gold to keep well-geared.
I hope this newbie warlock guide has told you enough to get you into the grove of things as you level!