NEVER auto-level.
For everybody that isn't a jedi, make them learn melee weapons feats. Make Jedi's learn lightsaber ones.
If you want somebody who's better at taking out a lot of weaker opponents, upgrade their two-handed skills. If you want somebody who's better at taking out single but stronger enemies make them learn dueling which is for one hand.
At Dantooine, go to the crystal cave to get good crystals from the egg sacks (you should do this before getting 2 star forge maps...) and you get them by targeting them and selecting up on the D-pad (like changing a grenade type) to bash them open.
Make sure you download the Yavin Base Station from Live because it's basically just a shop that buys your racing bonds (this is your payment for winning races) at about twice the price of other places and generally gives the best deals in the game. It expands in the items it has after you find two star forge maps and again after you find 4.
Since you're at the beginning, make them learn toughness, advanced toughness, etc. in order to give you a lot more health.
Don't level up charisma and make the main character learn the dominate mind force power for persuade since you can use force powers soon.
One robot is better at security and the other at computer use so whichever one is already leveled up a lot in that keep leveling them up in that but you'll rarely use them.
It's best to play this game with a soldier. If you want to make it hard play with a scoundrel.
If you use the force power for running fast (convenient) then you can't use any armor other then a jedi robe but you have to learn the feats for heavier and heavier armors in the first place.
Master Speed (thid speed upgrade) upgrades your defense in fighting I believe.
Don't learn destroy droid force powers until your third planet.
If you want to be light side learn stun/stasis.