I just finished reading “The French Ingredient : a Memoir”, by Jane Bertch. It’s the story of how she opened La Cuisine Paris cooking school in 2009. She visited Paris as a teenager and vowed never to return, but was transferred there by the bank she worked for in London, decided that banking wasn’t for her and what she really wanted to do was start a cooking school.
She ends each chapter with a tip on living in France and one of the ones she mentions is that you always, always, say “Bonjour” when entering someone’s establishment - I’ve read that same advice many times on this forum.