Locate your property lines, if you are not sure about them. Verify them with your property plat (the surveyed and court-recorded description of your property you got when you bought the property). Walk your property lines and visually confirm your markers and landmarks. Measure your property lines. You will need to know theses distances when you set up your first line of defense. Draw a diagram of them by tracing your property plat or redraw them freehand so you will have them to look at when designing your security plan.
Buy and install solar-powered motion sensors with lights at your property line. This is your first line of defense. Mount them so that they come on shining toward your dwelling and not into the neighbor's house. Adjust the sensors so they come on only when necessary. Purchase the brightest, most powerful wattage/lumens available. You want a bright light to see your intruder clearly. Make sure the light paths intersect, so there are no huge areas left in the dark when they come on.
Use trip wire along your first line of defense. String cans filled with rocks or pellets on your trip wire. Combine this with open space. Cut down any dense undergrowth and anything that may be a good hiding area. Consider putting up fencing at the edge of your most vulnerable areas. Use barbed wire or some other fencing that will not obscure your vision in that area.
Position security cameras at likely intruder entry points. Hang them high enough to get clear facial shots. Link them and tie them into a VCR which is linked to a security company that offers 24/7 monitoring to signal police. Check them frequently as you go about your day.
Buy the house alarm with the shrillest, loudest warning horn you can get. Make sure neighbors a mile away can hear it. Sudden loud noises often scare off already nervous intruders. Use grade 2 or higher deadbolt locks on all your entry doors. Learn to live defensively. Resist the urge to turn on a light in every room you enter and leave. Keep personal protection near. Do not open doors, especially at night, before knowing who is at the door.