First, external lighting that is motion activated. Make sure all of your windows lock properly. Worse case is Amazon sells a window lock that clips on. For your doors, if you can not account for all keys, either replace the lock or have a locksmith rekey it. Most break-ins happen through the front door by kicking it in. Replace the hinge screws with long screws that go into the door frame stud. Same with the strike plates. They also make strike plates that are longer and connect both the door knob and deadbolt. Reduce spots that can be used to hide while breaking in. The goal is to make your house look harder to break into than your neighbors. An alarm sign also helps. The actual alarm is optional.