30,000+ XP in 10 minutes cheat
I figured out how to get as many XPs as I like. In the Sith Enclave on Korriban, in the training room, where you find Sith training against prisoners, if you slice the computer using T3, and hack the datafiles (costs me 0 spikes) repeatedely, you gain as many XPs as you want. This may be possible elsewhere, but I haven't tried it.
Just keep doing it over and over again, and when you exit the screen you will have TONS of XP points. I was most dissapointed to find out that level 20 is the highest you can ever go, as I wanted to max out some feats I still needed. I leveled up 4 times though. Turn up the difficulty after that, if you get bored.