As I said in my post, the origin worlds are all pretty well balanced provided you do all of the quests on that planet and not skip any. I've also found that there's a logical order you go through with these quests which is basically just completing everything in the area and moving on to the next area which the game leads you to through the next class quest.
I looked up the quest you were talking about and to be honest, I don't really know what other advice to give. Everything on Tython is pretty simple if you just go through and do everything in all of the areas. The experience points you get from turning in quests and doing bonus objectives in those quests (pretty much all of which can be completed as you do the quest normally) will level you up pretty easily.
If all else fails, you could just ask for help from one of the other players that are on Tython, I'm sure someone would be nice enough to help out.