It's really up to you. What do you want to do? Do you want to take an active part in the supposedly existing Galactic Civil War? Do you want to serve in a neutral government? Do you want to work for a corporation? Pilot? Ground pounder? Doctor? Priest?
Yes, there are alot of options. Find something that interests you, even just a little, and check it out. Ask their leaders questions and see if it's right for you.
Just keep in mind that money isn't everything. A good faction will supply you with a ship or vehicle and, eventually, equipment.