A lock on a flimsy door is about as effective as locking your car door, but leaving the window down!

• All outside doors should be metal or solid wood.
• If you use a external door with a window in it, choose a key activated deadbolt rather than one with a simple knob or lever.  This will keep an intruder from simply breaking a door-window and reaching inside to defeat the deadbolt. 
• If your doors don't fit tightly in their frames, reduce an intruders ability to attack locks by installing weather stripping around them.
• Install a peephole or wide-angle viewer in all solid entry doors so you can see who is outside without opening the door. 
• Don't rely on chains as they break easily and don't keep out intruders- use the deadbolt.