You can bring in your pistol, but the magazines must not be capable of holding more than 10 rounds, unless those magazines were lawfully possessed in California prior to the ban on January 1, 2000.
You can carry the gun in plain view, unloaded, along with loaded mags in a belt pouch, as long as you are not within 1,000 feet of a K-12 school. Day care centers and preschools are not part of the 1,000 foot exclusion zone.
You can carry the gun loaded only if you are in an unincorporated area of a county where the discharge of a firearm is lawful. You may not carry a loaded firearm in public within the limits of an incorporated city unless you are lawfully hunting in an area where hunting is permitted. You may lawfully carry a loaded firearm in your place of temporary residence such as a campsite.
You may not conceal a handgun in a vehicle or on your person without a California CCW permit. Handguns in plain view or worn openly on a belt holster are not concealed under the law.
Handguns are required to be transported unloaded in an enclosed, locked container while within 1,000 feet of a K-12 school. Ammunition may be in the same container, but it cannot be in the chamber or in a magazine inserted into the firearm.
You may not carry a gun in any state-owned park or beach, or into any court house, jail, prison, detention facility, or government building or on the grounds of any school.
If I missed anything hopefully someone else can post it.