Start with Locks and Doors
Entrance doors are obviously the easiest way to gain entry. In many homes, a hard swift kick on the front or back doors will literally drive the door right out of its frame and the thief can just walk in and help himself. Most homes are originally equipped with inexpensive spring latch locks that have a short rounded locking finger that slides into the casing around the door. Upgrade your locks by removing what's there and installing dead bolt locks. Even better, double dead bolts locks (that need a key to be unlocked from the inside) provide the best security.
Good dead bolt locks have a "throw" (the metal finger that sticks out when it’s locked), about an inch long that actually goes into the door frame, not just into the light wooden casing around the door. Dead bolt locks are available at your local home store and they come with easy to follow installation instructions, but if you're uncomfortable changing locks yourself, a good handyman can do it for you.
Upgrading locks are a great start, but don't forget the screws holding the lock and door hinges in place. The strike plate on your door jamb and the hinges on your door are probably held in place with screws that are about 1" long - just long enough to fasten into the casing lumber. You can upgrade the strike plate with a much longer strike plate 10" or 12" and install it with 3" screws. These screws are long enough that they will go right through the door casing and into the 2 x4 or 2x6 framing lumber around your door. The longer strike plate will also accommodate 6 or 8 screws for fastening it. Remove the short screws fastening your hinges as well and replace them with the 3" screws, and your door will now be firmly fastened into the door frame. No one is going to kick that door out of its frame.



