WoW has a ton of competition for gaming & advertising services. If you want to get in on the ground level with less competition for a game that already has 1.6 million downloads at cnet in a little over a week (it's been popular in Korea for 3yrs), I highly recommend War Rock.
http://www.warrock.net/
I would use many of the successful marketing plans for WoW and use them for this game.