There are some great organizations in the Bay Area dedicated to defending and advancing tenant rights in California. Some of them are:

Tenants Together offers a Rent Control Toolkit, as well as a Tenant Rights Hotline, which will help you understand your rights as a tenant, and how to approach problems with your landlord. Note, that Tenants Together does not provide legal counsel.

Causa Justa focuses on equal rights for people of color, immigrants, women, and all oppressed and exploited people. Through rights-based services, policy campaigns, civic engagement, and direct action, Causa Justa works to improve conditions in Bay Area neighborhoods. The also offer free tenant counseling and case management for low-income residents of Oakland and San Francisco. Causa Justa does not provide legal counsel.  

The East Bay Community Law Center focuses on defending eviction lawsuits against low income tenants. If you do not qualify for their housing services, they also offer a referral service. Call (510) 548-4040 to get help.