I've worked as a shelf stacker in a supermarket, on the till at a well know book store, in a factory stacking boxes, on the till for a well know motor factor, and now work as a lab tech.
I wouldn't reccomend working in a supermarket full stop.
I found I could deal with the customers. They didn't really ask much.
At the motor factor I was better as I like cars a lot and could answer questions knowing I would look good as I knew what I was talking about. Phone calls and the PA system were frightening at first, but I learnt I could deal with them.
Being a lab tech is great. I deal only with my team, and we usually don't have much work on.
But I'm probably going to leave to study at college again. Hopefully this time I won't let my AvPD stop me from getting my degree.