Efficient Leveling
World of Warcraft is designed for efficient leveling. Experience gained is maximized by moving through zones, completing all the quests for your level, then moving on to the next area. This sometimes means coming back to a zone to finish quests that were above your level initially. For those who look ahead and want to get their flying mount as quickly as possible, the best method is to do every quest in every zone, as long as the quests are still yellow, along with as many instances as possible. It's quite possible to have your flying mount by the time you turn level 60.
The Zone Guide is out-of-date since the launch of Cataclysm, but has been left so that new players have an easy method to figure out which zones are on which continent. We will get it updated eventually!
Zones in blue text are found in Eastern Kingdoms.
At Some point everyone should consider doing the quests in all starting areas, for
reputation and achievements. Rep rewards give discounts and extra mounts.