Three things that will scare French people away
Bonjour à tous,
First of all, excuse my English. I am French. ^-^
Avoid asking personal questions, especially questions related to money. The subject is not taboo when appropriate, but it not either the center of our daily life. Asking "how much money do you make?", or "how much did you pay for your house?" can make a French person uncomfortable.
One of the first things French children are taught is to put his/her hand in front of his/her mouth when yawning. If you forget and open your mouth big, don't be surprised if surrounding people try to embarrass you with a "please, put your hand in front of your mouth, I can see the color of your underwear". French humor.
French people are more superstitious than Americans, and when superstition comes with bread, the whole nation fears. Sacrebleu ! Never, never, never, place the loaf of bread upside-down. The flat part must be on the side of the table in order for the father of the family to bless it with his knife before eating (this tradition do no longer exists).
One says that, in the Middle Ages, the executioner's loaf of bread was kept upside-down at the bakery so the executioner could identify it easily.
By turning the bread on its bumpy side, you are cursing your host. Oh là, là, là... Do not do that.