How do you keep tresspers off your property?

my neighbors and I have been experiencing a problem with people tresspings in our backyards. My neighbors have their cars broken into several times , but nothing of value gets stolen , and I have seen footprints left behind in the snow from someone other than my family members. I have bought a security camera but i have not caught the culprits in the act yet. This sometimes worries me so bad that I can't sleep. this is driving me crazy.