Race at the Tatooine ,get the racing bonds, DON'T SELL THEM YET!! Now, go to the Yavin Space Station. Sell them here for 160 credits. It may not seem like much, but when compared to how many of them you get and that they only sell for 60 credits elsewhere, it's very good.
After you reach Korriban, you will go into the Sith Academy. There is a twilek named Yathura that you can talk to for the Sith Code (you need to memorize this for prestige). If you ask her about the Sith Code, she will tell it to you, then ask if you have any questions. Say no, and then exit the conversation. You will have gained 150experience points. Now go back into the conversation and repeat. Every time you do this you will gain 150 points. You don't even have to exit the conversation. After Yathura asks you if you have any questions, say no, and then ask one other thing. After she is done talking about that, you can ask about the Sith Code again. The experience just keeps adding up.
After you get the last star map co-ordinates and before you go to the Star Forge system, go back to the Yavin station and be sure to have 40,000 credits and a good team. When you get to the main room the Rodian (can't remember his name) will start to speak but will be interrupted by five or six Trandosians coming out of cloak who will start a fight.
After you defeat them talk to the Rodian and he will show you his secret stash. In it are two items called Mantle of the force and Heart of the guardian, costing 20,000 each. They are color crystals but they modify any other power crystals in the lightsaber. The Mantle of the force is a sky blue blade and the Heart of the guardian is a orange-red blade (looks amazing). Mantle of the force keeps your saber on unless you press "x".
In your game dir edit swkotor.ini and under [Game Options] add EnableCheats=1 then when playing press ' to bring down console and enter any of these cheats below (the console will be at the upper left of the screen):
(number) = eg. 10 up to 999
giveitem (item name)