I'm a carpenter and at the time I was a house framer. Well the builder had discarded a number of sections of white picket fence that had set in front of the sample house. I rescued them and reused them out front of my place. One of those had a metal placard with the security company logo on it. So I just left it attached and fully visible at the front gate. It was a decoy. There wasn't any security system other than our dog. I figured,who's going to want to find out?
I have actually done alot of this myself another trick not listed is leaving coins in a easy to see places outside the house and IF they disappear someone has been there. Replace eventually you will find a thief. For pennies well use quarters everyone will pick up a quarter.
if you leave your house, place a $10 bill on your coffee table that is in plain sight of your picture window..when you get home make sure the $10 bill is still there before you enter