LA is way overcrowded and rentals are tough. Craigslist is a good source, but you must beware. Do you have any USC adviser to help out ?
What's your maximum rent / month?
Also, you can look into bulletin boards through USC's housing department and also their classified section. As this a living situation with another person(s), make sure to ask questions about the living situation; such as, are they smokers? an early bird or night owls? Do they have frequent visitors? Do they work out of the house? shared common area? parking? laundry facility? furnished or non-furnished? walking distance to USC campus? security deposit and so for? Here is the direct link:
Go to http://www.WestsideRentals.com. Or http://www.RentGMG.com. You should be able to find all your answers there. Those are the two sites I always recommend.
You can also try driving around the neighborhood near USC where you will find plenty of "FOR RENT" signs, specifically for students.