Keys in door - Don't make it easy on a burglar by leaving your keys in the door or your door unlocked.
Identify Entry Points
Before you make security improvements, identify those entry points most likely to be used by a burglar. You can do this by answering the following questions:
Which entrances are hidden or out of view from my neighbors?
If I am locked out of my house, where could I get in without too much difficulty? Every door or window you list in response to these questions should be a number one priority.