I got the sense that these optional businesses will rake in extra money automatically, but you can also help out by operating businesses yourself (like delivering drugs in a food truck). Volition showed off a few examples, including a food truck dispatch that also peddles drugs, arms dealers, car repo shops, nightclubs, and laundromats. As you grow the new Saints crew (company?), vacant lots across Santo Ileso can be purchased and turned into crooked businesses.