I used to be crazy anal about completing every single quest until I got to all of the instance quests. But now with the random dungeon finder I would only pick out fun or easy quests to do. Definitely skip any collection quests.

So leveling a new team, I would just hit quests that are quick with a good reward like this Wanted: Ragemane's Flipper right at 75 so my tank gets a decent upgrade... then back to running instances to level/gear up.

That's just an example. I would wowhead the zone I was in and see if there were any good rewards from quests that were worthwhile, etc.