For under $30 you can install motion detectors on outside floodlights at both the front and rear of the home.
Etch your driver's license number (not your Social Security number) on TVs, appliances and other goods. In the event of a break-in, this can make recovery somewhat easier.
Trim bushes or plants that obscure doors and windows or offer safe hiding spots for criminals.
Install deadbolt locks. Installation kits are inexpensive. Buy key-operated locks without inside knobs. Remove the key. Thugs who reach through broken door glass can't turn the knob to open the door.
Foil thieves who jimmy locks on sliding doors. Cut dowels to length and place behind the slider to stop the door from opening.
Padlock outbuildings or storage sheds where ladders might be stored.
Cover basement window wells. Consider covering basement windows with plywood. This provides a visual deterrent.