Doing every non-heroic quest on each world will get you more than enough experience to be well ahead of quest level. Always swing by the starport on each planet on your way offplanet to pick up the 'Bonus Series' that opens up. Often nice rewards and more easy exp.
Also if you're still having trouble always be sure to log off in the nearest cantina or on your ship so you'll earn 'rested exp.' That will double your exp and make you level even faster.
This can all be supplemented by Heroics...if you can find a group to do them with... or Space Combat missions if you cant. Space missions are really like free experience since you lose nothing if you fail. Can also try PvP for extra exp too.
In short its hard not to level up quickly in this game.
Edit: just noticed this was a necroed 2 month old thread. I'm guessing you figured this all out by now