"Comfort has its place but it seems rude to visit another country dressed as if you've come to mow its lawns."
-David Sedaris, "Me Talk Pretty One Day"
The six rules of appropriate behavior:
1) Do not smile.
2) Learn how to flirt correctly.
3) Excusez-moi de vous deranger, monsieur, mais j'ai une probleme.
4) Saying bonjour (-monsieur/madame) isn't good enough.
5) Shaking hands is perfectly acceptable, but in France one must also "faire les bises." Two to four kisses is the norm.
6) Regardless of your affluence, your appearance determines how you will be treated.