UCSD requires most of the undergrads to take some form of calculus. Not all of them are good at math and many will seek out additional help beyond that which is offered by their instructors and TAs. This presents a great opportunity for you in the form of private tutoring.
NOTE: You cannot tutor students enrolled in any class for which you control the grades. There is an obvious conflict of interest.
The question remains: how does one find students, especially if you cannot tutor your own students. Well, students from your first class may seek you out the following quarter if they enjoyed having you as a TA. Alternatively, you may let your fellow graduate students know that you are interested in tutoring and ask that they send their students your way.
Another way is to send an e-mail to the Mathematics front desk office at email@example.com. The front desk maintains a list of math tutors. You can ask to be added to the list. You need to include your name, a way to contact you, what level of classes you feel comfortable tutoring, as well as your asking price. You might want to ask for a copy of the list first to see what others are charging.
It should be noted that this list seems to be primarily used by parents in Carmel Valley looking for tutors for their high school children. This typically involves driving off campus to meet with them, which could pose a problem if you do not have a car.