Wasted alot of time on silly colection quests on my way to level 45 on first team, so not realy sure whre its best to go there.

But fromlevel 45 as alliance, its atleast possible to do the following without needing to do collection quests:

Searing Gorge (alot of kill quests with high exp) ->

Hinterlands (decent amount of kill quests) ->

Western Plaguelands (make sure to do cauldron quests, and the quests aviable at farmhouses close to each caluldron) ->

Eastern Plaguelands (the old Naxx handin quests are great if you allredy have the stuff needed for them lying around) ->

Outlands at level 58



On my next team i level up, i plan to go to Westfall at level 10, followed by redridge and duskwood, then on to STV and Tanaris. This is where i hope to become 45, and redy for the zone path i allredy know will work.

To get to the long travel places (Tanaris, Searing Gorge and Hinterlands), i used my level 70 chars and summon firend ability. (its fast to walk from hinterlands to WPL, by following the path leading to Scholo, no need for summon here)