You don't need to spend lots of money to feel more secure in your home but you do need to have a plan. Most homeowners put little or no thought into home security and, as a result, the thieves benefit. With some observation and careful thought you can create a plan that makes thieves skip your house and move on to something easier.
The plan starts with the realization that there is no such thing as absolute security. The goal isn't to turn your home an impenetrable fortress. (Although there is something romantic about the idea of living in a castle with a moat.) The goal is to make your home an unattractive target for thieves. This can be done without turning your home into a prison compound or breaking your budget.