I remember my Dad telling me to make eye contact with everyone. Look around, make eye contact. If you hear someone behind you, turn and make eye contact. They are less likely to do anything to you if you have done that. Always walk with confidence, don't look at your feet or phone. Stand tall, look around, constantly scanning the parking lot. Even if you are with someone else, do both of these. Also when we had keys, put your keys between your fingers. if someone approaches you, you can scrape or startle them enough to get away. People aren't your friends, no matter how friendly they look or act.