What matters is taking the dark side choices in the main plots. Actually, you don't have to be a complete jerk to everyone you meet. You just have to make the right decisions. My level is at the very bottom of the dark side. Sith lords are meant to be the dark side equal of a consular and use the force. You won't be as powerful if you are anything but a consular and you become a sith lord. To be a sith lord, I recommend you start out as a Jedi Consular, and then progress to the dark side and choose sith lord. I am a Sith Lord and former Consular right now.
