Burglars enjoy using booby traps to throw you a curveball, and that is why it is good to keep an eye open for these. Usually screws to step in, or broken glass that do not belong, and so forth. Furthermore, look out for screwdrivers, hammers, shovels and so forth, that do not belong to you, that people can use to break into your home, and that they might have stashed away so as not to carry too much on the night, or day, that they want to do burgle you. Also keep an eye out on anyone loitering outside your home.
