Dead bolt locks on the doors, locks on the windows, and good lighting outside. Take a look at your landscaping. Do you have bushes and other hiding places up close to the house? Don't leave a ladder outside where someone could easily use it to climb up to a window. Sounds silly, but most thieves use what's at hand in order to gain entrance. Try not to leave things around outside which would be handy for breaking a window. Glass panels in doors or particularly vulnerable windows should be reinforced with bars. Whether or not you put up burglar bars depends on the neighborhood. Some places, it's the norm. Get to know your neighbors. You don't have to BBQ with them, but do try to get on a first name basis where you know each others schedules and cars. A nosy neighbor can be the best crime deterrent.
Security cameras are only about $40 at Harbor Freight. Look at www.harborfreight.com There may be a Harbor Freight store in your area and if not, you can order on-line.
I hope this helps you :-)