Residential crime spikes during July and August as people set off on summer vacations [source: OIsen]. As mentioned earlier, if you are going out of town for an extended period of time, call your local police and let them know. Also, alert neighbors you trust about your trip and ask that they keep an eye on your property during that time.
More importantly, when you leave town, don't leave signs of an empty house. That will only make your house look like a giant bulls-eye to a thief. First, if you have a home phone, don't change your message to alert callers that you have left town. Also avoid having piled up mail, overgrown lawns and newspapers strewn about your yard that send surefire signals you're miles away.
Have a friend house sit or at least pick up your mail and newspapers. Ask them to move your car periodically to make it look like you're still around. During the winter if you live in a cold weather climate, consider having someone shovel snow from your driveway. In the summers, arrange for someone to cut your lawn.