I'd second Zagam's recommendation not to level as affliction. It's certainly possible but doesn't fit the run and gun style of leveling that most of WoW offers (at least until the higher levels). Destruction is very bursty at all levels from my experience, so in that regard its a great choice. With a little practice you'll work out a quick spell rotation that will have most mobs dead before they reach you, which you can repeat ad infinitum as you level up.
Also, if you find yourself in a tricky spot ever, just know that your voidwalker (or voidlord, if you choose to talent Supremacy when you reach tier 5) is a tough little blue aggromagnet nowadays
All of the rotation, talent and addon information is in the guides here on this site - while it is not custom tailored to lower levels, it can easily be extrapolated to be effective, so I strongly recommend you check the class guide for whichever spec you choose.