The best lock cannot function if you fail to lock it. Be sure to keep your doors locked.

All windows should have secure locks and frames. Many home invasion sexual assaults occur when the offender enters through a window on the ground floor.

All entrances and garages should be well-lit. Have your keys in your hand, don't fumble for them at the door.

Never open the door after a knock. Require the person to give their name. In the case of service persons, ask for proper I.D. and refuse entrance if you feel uneasy.

If you are living in a college dorm, keep your door locked at all times and never let a stranger selling anything inside. If you see any suspicious persons, tell your floor monitor or similar authority immediately. I have heard of quite a few cases where a person or persons appear to be selling perfume or the like inside a dorm. When the girl lets them inside, he or they attack her.

But let's not take away from the fact that most sexual assaults that occur inside a home are date/acquaintance rape. Follow your instincts, respect yourself and your body. If you feel uncomfortable, tell him to leave.