Increase visual deterrence by installing real or fake video cameras in conspicuous locations. The potential thief will be worried about being on camera and the possible existence of additional alarms so most will move on to easier targets. Place signs indicating there is a home alarm system installed. Deterrence is an important part of the home alarm system.
Increase visibility around your home by removing or cutting down shrubs and other growth around potential entry areas, such as windows and doors, and especially basement windows. A thief likes to be under cover when he breaks in, make sure he is visible to your neighbors and also from the street.
Install motion activated lighting outside. Nothing scares off a thief more than bright lights. Test the sensitivity so small animals don't set it off. Let your neighbors know this is part of your home security system.
Install wireless intrusion detectors on the windows and doors. These are readily available and quite easy to install. This is the final part of the do-it-yourself home alarm system and your final defence. A high pitched alarm will most certainly send the thief running off.