The San Francisco Bay Area is fortunate in having a rich diversity of model railroad clubs covering all of the major model railroading scales and gauges.  Joining a model railroad club offers several benefits including:

• Access to other members experience, skills, and mentoring to help you learn various aspects of the hobby.
  
• The opportunity to operate trains on a model railroad typically much larger than what one might be able to build at home.
  
• An opportunity to make new friends. 
  

Club membership also brings with it certain obligations such as supporting Open Houses, participation in the business of the club, and the willingness to compromise and accept club decisions (which might differ from what you might do on your model railroad).  However that is a small price for the many benefits they can offer.