Park in a well lit, busy area. Make sure your surroundings are safe prior to getting out of your car.
Do not leave valuables in your car.
Always lock your car when leaving it.
Walk confidently to or from your car with your keys held ready to open the door or to be used as a weapon.
Check the back seat or hatch for intruders before getting into your car.
Once inside, lock all doors and if possible leave windows up until you have reached your destination.
If a passing motorist indicates that you should stop, keep driving to a service station. If you decide to stop, stay in the car with the doors locked and the window partly opened to speak through. Drive away if you feel threatened.