When leveling your main class dont do every side mission leave some for other classes a rule of thumb I use is if a quest is 2 or more lvls below mine I save it for later. Guildhest and levequests help and also do the quests for GC seals as it kills two birds with one stone. Finally work on your hunting log while picking up as many fates as you can along the way. I forgot to mention you can rerun the story 4 person instances to also give exp and a boost in your gear.

Another way to help level is to work on your crafting so as to be able to make your own gear it will save you lots of money in the long run.