Jheusse

I cringe to add this to the discussion, since this isnt' a "trick" per se, and is simple enough it should go without saying (but I'm pretty simple so I'll say it).

The Ribbon Poles associated with the fire festival will give you a buff to gained xp of 10% with a stacking buff. If you stay on the ribbon for a full minute, you'll get an hourlong buff to xp. Repeatable.

I add this because I wouldn't have known about it except a guildie told me. Repeatable 10% bonus to xp is nothing to sneeze at.