I was able to learn how a retail store worked on a daily basis. Also, I learned how to interact with people of different backgrounds and personalities.
What I wish was different
At the same time, I took a summer class at my local community college. I wish that I had prepared myself to be working for most of the week, as well as weekends.
Advice
Don't be afraid to speak about things that bother you. Also, push yourself to speak to people to get a sale: you don't know until you try.