Level by slaughtering your fellow players. Which means jumping into a battleground for a change of pace won’t completely bring your WoW power leveling progress to a halt. You can start battlegrounds at level 10 with Warsong Gulch and Arathi Basin, with more battlegrounds showing up as you level.
To get started, just open the Player vs. Player menu (it’s the faction icon in your button bar or “h” on your keyboard) and pick the battleground you’d like to run, or choose a bonus battleground — either random or the week’s Call to Arms battleground — for extra rewards. In addition to experience, you’ll also get honor, which you can use to buy PvP gear and other goodies.
Difficulty can vary a lot. If you don’t have good gear or a good team, getting through a battleground could be pretty painful. But when you do wind up with a good team, battlegrounds can be fast and fun.
Though we couldn’t recommend this as a primary leveling method, it’s also not the worst way to get experience.