I've seen some stuff on wotlk lvling advantages so I wanted to put some of them together and add my own. (my first try at contributing , be gentle plz)
kk, first things first, if your toon is not 70 yet, before you hit the 70 mark go to an inn and leave your toon rested for a week. in BC, alot of people found their toon fully rested after they increased the lvling cap, thats because wow still records your full rested xp untill your 70. So park at an inn, be fully rested then ding 70.
also, get all your dailys and do them but do not turn them in, as soon as expansion comes out you can turn em in for quick XP.
one other one that I havent seen mentioned here at all is the brewfest buff.
take your 70 toon and on the last day of brewfest get the 2hr 10% xp buff and log out till the expansion, its not too fun but it does give you a nice advantage over everyone.
theres also the invite a friend thing, where you make another wow account and port the toon to ya ( you have the ability to summon your friend anywhere) and turn in the quest for the added xp.
btw the invite a friend buff works on quests, just doesnt work with mobs.
so heres a compilation of everything ive found over the net to give you a head start in lvling your toon to 80.
GL =D