You can prevent an emergency lockout by being conscious of what you are doing when you are locking and unlocking doors and windows. Make sure you have everything you need to avoid misplacing keys or leaving them behind by accident. You can try remembering to recite a mantra that helps you stay accountable of everything you need to have before locking any doors. You should also have an emergency key that you can access in the event of a lockout, even if you leave it with a relative or close friend. This way, you gain access and can worry about replacing your keys after you are back in your home or car.