This will help deter someone from duplicating one key and having access to your entire auto. Consider special locks for such parts as hub-caps, gas caps, etc. Also, a hood lock could protect things such as a battery, engine, etc. The hood lock could also prevent thieves from trying to tamper with certain electronic alarm systems. If lost or stolen, at least the thief won't have access to both.
Thieves know most all the hiding places.
Park in well-lit areas that have heavy traffic. Avoid areas that are unattended or poorly lit. As police departments break up these crime rings, they try to locate the owners of the many parts they confiscate. If you are attending a club or going to Party or social event. When returning to your parked auto, always check your back seat for intruders.