Perhaps this goes without saying, but "Surfing California" by Bank Wright is essential.  It's a paperback and probably at Ron Jons for sure.  If not, Amazon has it.  It's a great book and Bank Wright is a class act for sure.  You can have one of my copies if you want (I can mail it).

There is always surf there (Central California....Northern California for those surfers who care about stuff like that, even though Northern California technically starts on the north side of San Francisco Bay).  Most people surf in packs because it always feels a little safer.  Surfing alone is a bit unnerving up there because of the Great Whites.

Don't go cheap on the wetsuit.  It's better to be warm and stiff than cold and stiffer.  Unless you're a die-hard athletic shortboarder, you're going to get cold in anything but the best gear.  Booties and a hoodie will keep you out longer.  

The waves get big.  Know your limits.  It gets just as big and serious as Hawaii.

If a local gives you crap just tell him, "You don't know me.  Don't talk to me."  Unless, of course, you screwed up.  In that case you apologize and leave.

Finally (and I always get crap for saying this):  Don't call it Cali.  Kooks call it Cali.  Might as well call Florida Flori if you're going to do that.  People born and raised there aren't in such a hurry that they need to shorten it.  The reason? Why would we shorten the name of the nation's best state?

Bob is my numero uno Grandpa.