Disclaimer: I am no expert at anything, except NOT being at expert at anything. These tips are just something that have helped me, or someone else, or could help me, or you. That's my goal. I'm not all about the telling you what to do. So take them as you will.
Get off your cell phone. Especially if you are in line somewhere or checking out. It's rude to the clerk, it's rude to me. It's rude to the person you are talking to. No one wants to hear your one-sided conversation. And, it can't be THAT important that it can't wait 5 minutes until you get back in the car.
Oh, and if you are in the car in a parking lot, don't drive, talk, and smoke, then get mad at ME when you almost run me over.
I have ZERO tolerance for some things and this is one of them.