Securing your apartment is your first line of defense against getting burglarized or worse. Zillow.com helps you make sure your castle is a fortress.
The most important life-saving items you need to have in your apartment are smoke detectors and a carbon monoxide detector. However, they won't do you any good if the batteries aren't working. Be sure to test your detectors when you first move in and to change the batteries when the time changes in the Spring and the Fall.
If your building has a single outer door, call your landlord immediately if the locks don't work. Those outer doors are the first bit of security keeping ne'er-do-wells from entering your apartment. Also, if you have buzzer and a stranger buzzes and asks to be let in, don't do it. Either don't answer the buzzer or go and see who is trying to get in. If you just let anyone in, you are inviting solicitors at the best and criminals at the worse to harass yourself and your neighbors.
If your door doesn't have a deadbolt, ask your landlord to install one that extends into the door frame far enough to keep burglars out and always use it. When someone comes to the door, look through your peep hole to see who it is and if you don't know them, don't open the door. If your peephole has paint on it, scrape it off or put in a maintenance request.
Additionally, if you live on the first floor, be sure all your windows can lock or have grates. Also, never leave your blinds or curtains open when you're away from home, just as you wouldn't leave valuables out in plain sight in your car. Finally, get renter's insurance just in case you are the unfortunate victim of a break-in.