Quote from mgookin:
...But, the greatest deterants to crime are alarms and dogs. Get some ADT signs in your yard (call a salesman and get an estimate; he'll give you free signs) and put a big, dirty, chewed up dog's bowl, dog toys, etc. by the front door with BAD DOG signs.
Another very good crime deterent and the simplest is lighting. I like the chewed up dog's bowl with the "BAD DOG" sign idea.