World of Warcraft an MMO game and like any other game in this genre there are efficient and non-efficient ways to level. I have been playing WoW for more than five years now and am a veteran of many other MMO games and I will tell you there is really only one efficient way to level your characters.
Simply put the most efficient way to level a character in any MMO that has a quest based system is to do the quests. Of course questing alone is not enough to make the levels shoot by; you have to put a little more effort into it.
When you are given a quest that sends you from one end of a zone to the other to kill a certain mob or explore an area etc. you need to take full advantage of every possible experience point along the way. What I mean by that is when traveling you should kill your way to your objective and back. If the mobs you are running by are in your level range and you get experience for them KILL them. Doing this can turn a low experience quest into something that goes a good way toward helping you level.
One of the best ways to maximize your experience vs. time ratio is to take every quest in an area and then work your way through them before running back to turn any of them in. Add what we discussed above to it and your experience bar will move along nicely.
There is an add-on called “Quest Helper”, you can get it at curse gaming. It literally leads you through the quests you have in your log in the most efficient manner. Simply follow the on screen arrow.
There are those who say that grinding is the only way to level quickly. In my opinion they are wrong. Suppose that you get a quest that awards 800 experience points and takes you 15 minutes to do. If you kill your way there and back you will earn significantly more experience than staying in one spot and grinding. Most quests award items and cash as well as experience and that is something that grinding usually does not offer.
To conclude, the most efficient way to level your characters is to fill your quest log with every quest you can get in a particular zone then kill your way through them. Don’t forget to give Quest Helper a try as well.