Don't buzz someone inside unless you know the person.
Don't get on the elevator with a stranger if your own good judgment warns you against it -- need an excuse to avoid embarrassment, say something like:"Oh, I forgot my mail."
Have your key ready before you get to the front door.
If a stranger wants to use your phone for any kind of call from business to emergency, keep them out and you make the call for them! Any problems or in doubt? Call the police!
If there are glass panels in or near your doors, reinforce them in some way so that they cannot be shattered.
If you arrive home and find your door open, do not go inside. Call the police from a cell phone, pay phone, or neighbor's house and ask them to meet you.
If you live in an apartment, don't be polite and hold the lobby door open for a stranger who has been waiting.
Install a dowel or a pin to secure a glass door to prevent the door from being shoved aside or lifted off the track.
Keep spare keys with a trusted neighbor, not under a doormat or planter, on a ledge, or in a mailbox.
List only your last name and first initial on your mailbox.
Lock all doors at night and every time you leave the house, even if it's just for a few minutes.
Lock all garage doors when leaving the house.
Lock all windows, even when they are opened a few inches for ventilation.
Lock sliding doors every night and each time you leave the house.
Make sure all doors are solid hardwood or metal-clad.
Make sure all entryways have a working, keyed entry lock and sturdy deadbolt lock installed into the frame of the door.
Make sure every window in the house has a working key lock or is securely pinned.
Make sure sliding glass doors have strong working key locks.
Make sure the door leading from the attached garage to the house is solid wood or metal-clad and protected with a quality keyed door lock and deadbolt.
Make sure your doors feature wide-angle peepholes at heights everyone can use.
Make sure your entrance area and all other areas around your house, garage, and yard are well lit. Keep outdoor lights on in the evening -- whether someone is at home or not, or install a photocell or motion-sensitive lighting system.
Make sure your house number is clearly displayed so police and other emergency vehicles can find the house quickly.
Put a lock on the overhead garage door so that you do not rely solely on the automatic door opener to provide security.
Trim shrubs and bushes so there is no place for someone to hide.