Stop by your career or student center to look for job postings. No matter where you go to school there should be a central location usually not far from the counseling offices where jobs are normally posted, and this is an excellent place to find temporary jobs for students. If you aren't certain where this is make sure to check with someone else because nearly all academic institutions have them.
Talk to your financial aid office about enrolling in a work study program. This is an excellent way to find on campus jobs that are temporary, usually lasting only one semester or less. The benefit of work study programs is that the money can be applied directly to your tuition if you'd like, reducing the amount that you'll need borrow for your student loans.
Call some of the local businesses near your college and ask if they are hiring. Most local businesses near college campuses are used to hiring students for only a semester or a few months. They generally pay well and understand if you aren't looking for long term employment.
Ask your professors about helping you find paid internships. If you are at least half way through college you can start to think about doing an internship and some of them pay really well. The nice thing about internships is that they are almost always temporary and you can build lasting contacts at the same time.
Sign up to receive emails from your school about new jobs. For example, if you are a psychology student you can sign up to receive emails from the psychology department about upcoming student job opportunities related to your field of study.