From SFWiki

San Francisco State University is located on the south-east corner of the city. It is next to Stonestown Mall and near the Merced Branch of the San Francisco Public Library. It is about 10 minutes walking distance from Lowell High School.

To get to SFSU with public tranportation, take MUNI lines 26, 29, 28, M. Other, slightly less nearby lines, include K and 17. There is also a free shuttle that goes to and from SFSU to the Daly City Bart Station. It comes around every 10 minutes on weekdays. The 28 runs the same route, but more regularly and on weekends.