Just to be clear, you can't carry a loaded weapon legally in California, openly or otherwise.

Furthermore, I'm surprised your LEO friend advised you to carry a firearm when it appears that you don't have much experience in using them.
You're placing yourself in a dangerous situation if you face off with people able and willing to use a gun against you when you have no experience or desire to wield a firearm or shoot someone in self-defense. My own personal opinion and experiences have led me to conclude that the order of least dangerous to most dangerous would be: willing to wield, willing to kill > unwilling to wield, unwilling to kill > willing to wield, unwilling to kill.

My guess is you're in that last category and you can maximize your survivability by remaining in the second category while raising your situational awareness.