Well, I just went from zone to zone, expansion to expansion doing every quest that I could find and would work. When there weren't any, I would run around from flight path to flight path and found do-able quests along the way. It's not easy, but discovering places also gives xp. That's how I did it, so I'm sharing. You may find a better way. As it stands though, I am stuck 3/4 of the way through 109 toward 110. Also, from Dalaran watch for the dailies to fight the Burning Legion. Those give good xp as well.
