I would quest but thats me, i cleared all instances before i hit 80 on my first team.(well not the oculus) My second team wich i just quested with went faster and earned more gold.

Unless your an achivment freak DONT DO THE MOJO QUEST IN GRIZZLY HILLS!!!

The fastest way is to only do kill quests in outlands and go directly to northernend at 68 and keep on questing.

If you still plan to do instances in northernend start early to look for cheap tank items on AH. Having a well geared tank makes most non heroic instances easy mode.