SIMPLE! Keep your car interior empty.... "IF" you have anything valuable put it in the trunk BEFORE you park your car, it will REDUCE the chance of a break in.
A thief will NOT break into a car just to see what is inside... He is after something that is visible like your camera, cell phone, lap top, Christmas pesents, GPS, etc.
Breaking a side window is easy with a spring loaded centerpunch and it takes 15 seconds to "smash and grab" your items. Stealing a car takes (two guys) less than 90 seconds even with "anti theft" ignitions.
"Punching" a door lock (you will never know it was punched until you look under the handle) is easy with a screw driver and when they start making a "punch proof" door guard plate the "maggots" will find anther way to get in.
Prisons are a training school for amature thiefs to get a "formal education" on crime.
Sad to say there are "Jit Bags" just waiting to prey upon hard working peeps (like us) who take pride in having the finer things in life... $10 is alot of money to a junkie.
Motion sensors, dogs, nosey neighbors, well lit areas, cameras (even dummy type) seem to be the best deterrent for theives..... even then they will ignore the deterrent and make a hit.