I wanted to post this as something to think about when leveling an elemental shaman early in the game (Think below level 40). Most folks that come here will have leveled past this.
One of the most important things you can build towards is Crit Chance. You will generally have a good MP pool and the fights you will get in will not have you running out of Mana. Crit Chance is fairly easy to get, and the double damage from your spells will mean that you can cast less spells to kill a mob. Less spells means faster kills. Faster kills means faster leveling. The key to increasing this would be crit strike rating, if you can get it, or INT. INT is easy to come by, and I would encourage you to stack as much of it as you can.