I think the general theme here is DOGS. Alarm systems are good too but costly.
I believe simple steps like not flaunting "bling", keeping shades drawn at night, clearing brush and obscuring vegetation, GOOD lighting, and common sense go a long way in keeping thieves away.
I like being able to have at least one car parked outside and I have made a habit of whenever we leave the house unattended to wave vigorously at the house as we leave...giving the impression there is still someone inside