You don't have to spend a fortune to insure the safety of your family and home. I have listed several things you can do for little money to help make your home a safer place without having to install a complete home security system, which is definitely not frugal. In fact, few have the money to install such a system.
Install alarms
First things first. You might want to buy one of those small door-installed alarms that cost about $20 or less. Powered by cell batteries, once it's turned on and the door is opened, the alarm emits a sharp warning to alert you. It's cheap, unobtrusive and it works.
Bolts and locks
For doors and windows, you can install bolts and locks to reinforce an existing lock. As long as the bolt is solid and the hinges are properly screwed in place, you will have little worry. If you have sliding doors that don't have an anti-lift device, it would be a good idea to install one. Or, you could install two door locks - one on top and another at the bottom - to reinforce the hook lock.
Keep the light on
Illuminate your porch, back door and garage. If you're willing to spend a little, invest in dusk-to-dawn lighting powered by photoelectric cells. These save a lot of energy and will be cheaper to use than electric-powered lights. Even less expensive is a solar-powered spotlight that collects the sun during the day and lights the yard at night.
Keep things thorny
If you don't have a fence or wall, keep thorny plants and shrubs around. Plants like roses, holly and hawthorn have spiny leaves and thorny stems are great deterrents because they can produce punctures and tear at the skin. They not only provide you with security, they are also great ornamentals.