1.) Acquire a firearm and complete proper training and practice. Since you live in California, keep it in your home.
2.) Acquire legal self defense items: stun gun, pepper spray, etc. Keep a Maglite in your car.
3.) Document the stalking: photos, license plates, etc. and report it to the police.
4.) I would directly confront the stalker while he/she’s stalking me (while videotaping), but I cannot recommend that to anyone else because of the physical and legal danger involved.
Excellent advice.