Be there when you're not.
One of the quickest and easiest ways to deter burglars is motion-activated lighting around the home, illuminating would-be uninvited guests. The aisles of home improvement stores are lined with dozens of inexpensive motion sensor outdoor security lights at reasonable prices.
If installing a completely new security light isn't possible, check out existing lighting and swap it out for a motion-detecting unit at front, side, and back entries. A solar powered light allows for placement nearly anywhere without having to touch any wiring, though costs are higher and illumination less bright than wired models.
An audible warning after a locked door is pried opened or window broken might offer a few precious seconds to call the police, or hopefully scare intruders away with the blast of an alarm sound. A professionally installed alarm system isn't the only option — a budget solution: $4.50 glass break detectors on windows. Some models work by detecting vibration, while others activate when contacts are broken, but they're all effective and produce a loud and high pitch alarm. Available as complete kits or individual units, with higher-end models offering wireless monitoring/notification.
Oftentimes, burglars aren't even breaking into a home — they're taking advantage of a window left open or door left unlocked. While we can always try to remind ourselves to lock the doors, it's inevitable someone will forget while in a hurry. Install an electronic lock and you'll never have to worry about the kids running out of the house without locking up.
Security camera systems aren't just for keeping an eye on the home; they're an effective way to keep an eye on pets and children while away, especially now that many systems offer remote wireless/wi-fi accessibility. DIY kits are available online for a few hundred dollars, and existing webcams can be set up for remote monitoring with free software like Yawcam. Some models even allow control of camera movement over the internet!