Check the Web site and campus publications for announcements of the application deadlines in autumn and winter quarters. Many graduate students serve as teaching assistants to help pay the bills. To become a TA, you must be appointed by the dean of the College or the Master of one of the Collegiate divisions upon departmental recommendation. Research assistantships are also available, mostly in the physical and biological sciences. Appointments are made by faculty members.
Money varies according to the type of work and the time commitment.
The two largest employers of students are the library and the medical center. But don't limit your options, other university offices are always in need of student employees. You can find all of these job postings at the student employment web site. Both provide employment opportunities in a variety of secretarial, clerical, technical, and other positions.