Always keep car doors locked and park in well-lighted areas in sight of other people.
Be alert to vehicles following yours. If being followed, drive to the nearest police/fire station or anywhere large crowds of people are gathered. Do not drive to your home. Call the police!
Have your keys out and ready to be able to unlock and slip into the door. Be alert.
Leave only your ignition key with parking lot attendants or service station personnel, as they could make a copy of your home key for later use.