When moving into a new apartment, have the lock cylinders changed. Equip the door with a heavy-duty dead-bolt lock or a high-quality rim lock, and lock it every time you go out.
Be sure that the door panels and door frame are strong and that the door fits snugly into the frame. A space between the door and the frame makes it easier to pry open the latch.
Lock any windows and doors that open on balconies, fire escapes, or rooftops. If you live on the first or second floor, lock all the windows.
Never allow anyone you don’t know into the building. If suspicious persons try to get in, notify the superintendent. Don’t leave messages on your door or in the lobby indicating that you are out. Install a peephole in your door, and check who is there before opening your door.