The Crime Doctor site has a lot of great information on home security. In particular, they've got an article called "Home Invasion" that has a section called the Criminal Profile. It gives a bit of insight into what thieves are looking for when they target a home, and details that there are two different kinds of burglars: "residential burglars" and "home invasion robbers."
The residential burglars "work mostly during the day and when a residence is more likely to be unoccupied. Most burglars work alone and tend to probe a neighborhood looking for the right residence and the right opportunity. Alarm signs and decals, bars on windows, strong locks and doors, big dogs, and alert neighbors can sometimes deter burglars. Also, burglars will avoid a confrontation and will usually flee when approached."
On the other hand, the home invasion robbers "Home invasion robbers, in contrast, work more often at nights and on weekends when residences are more likely to be occupied. The home invaders will sometimes target the resident as well as the residence... Many home robbers have been in your home before as a delivery person, installer or repair vendor. Home robbers rarely work alone and rely on an overwhelming physical confrontation to gain control and instill fear in their victims. The greatest violence usually occurs during the initial confrontation and home invaders often come prepared with handcuffs, rope, duct tape, and firearms."
The article goes on to detail how these people get in and, more importantly, what you can do to prevent both types of criminals from targeting your home. It's definitely worth a read.
http://www.crimedoctor.com/
