Lock your car door. Even if you're only running inside to grab a jacket, you need to keep your car secure. Ten minutes is long enough to steal all of your jewelry. Advertise that you live alone. Use initials on your mailbox and for your telephone listing.
Criminals look for easy targets.
Don't make yourself one. Get on the elevator with only one person unless you know them. Once you're on the elevator, stand near the control panel. This will prevent anyone from stopping the elevator between floors. Leave valuable objects out that can be seen through your apartment window or out in your car.