Level Ups

[defiacne]

I'm kinda new to the RPG world. I've just been enilightened on how fun it is to develop a character. With that being said, I have a question that I wish answered by someone more qualified than me.
In the game, is it better to level-up when you get the opportunity, or should you hoard up your all your level-ups until you become a Jedi?
I am halfway through on my second go round and hoarded up all my levels until I became a Jedi and find that my character is much, much stronger than he was the first run through. Is it just my experiance that makes him better, or is it just a better strategy? Did I lose anything by doing so?
Also, is it your total level up that equals 20, or is it just each class max total 20? (ex. could you have Jedi 20 and Scout 8? or is it just Jedi 15 and Scout 5?)

Thanks for any help.

[fable]

There will be plenty of opportunities to make additional levels--in fact, you can keep on leveling as long as you don't mind mindless killing on a desert planet. So don't bother saving your leveling points.