When you aren't home, use a timer set to turn interior lights on and off at varying intervals as though your home was still occupied. Don't keep large amounts of cash or really valuable jewelry around the house. If someone comes to your door asking to use the telephone, make the call yourself. Don't invite them in. Don't hide a spare key under the door mat or under a flower pot.
Thieves know all the good hiding places.
Plant thorny bushes under all windows. Trim back any trees or shrubs near doors and windows to eliminate hiding places for would-be theives. Don't leave ladders outside. Keep any tools that could be used to break in your home safely locked away in a garage or shed. If you own a dog and go out of town, have someone come in and care for your dog in your home.