You get an xp buff on all classes except your highest that helps to offset the lack of quests. This xp buff effects xp from mobs killed and IIRC fates. Best bet is dungeons after you get to level 15. Also starter quests are all available in each of the 3 city states that should help you get to at least level 10. If you started in Gridania you can get to Uldah fairly easily, though it does require some caution in a few zones if you aren't at least level 30 already as there are some higher level mobs that can 1 shot low level players if you don't pay attention.