Well, you can talk about literally anything here - describe a certain day where you had to enter a store and the person working there was nice.
For example, I went to a jewelry store once to buy a present for my friend, and the lady working there was really nice and helpful. She asked me who the present was for, and showed me some beautiful wrapping paper for the gift, and was overall of great help. She was chatty and inquisitive (but not too much) and made me really happy about my purchase.