#1. Duty roulette daily bonus <--- this is almost a free level
#2. Fates <---- Do these wile you wait for duty roulette que
#3. Current level dungeon
#4. Fates
Repeat / Alternate #3 - #4
This is the best way to level untill they patch. I recommend saving you're leve's for crafters/gathers unless you have full 100. Then you can dump some into leveling a Disciple of war/magic.
If it's your first play-through, Keep doing the main story line. The quests are mandatory to open later dungeons and raids, And they also give a retarded amount of gold to get you started once you hit 50.