I think the biggest difference between Paris and even France as a whole and a lot of other place, starting by the USA, is that in France, the customer is not always right and defenetly not the King, period.

If you are not a paying customer, then get lost. There's millions other tourists lining up to be where you are.

If you are a paying customer, you are still expected :

• To show basic politeness which means saying hello when you meet someone, end your resquests with Please and be thankfull when they are fufilled. Keep doors open for other people, wait properly in the line... Use common sense.

• To not act as if the place belong to you, no matter what. Which means don't speack too loud, don't yell, don't do shit you wouldn't do in your own city. You're just another tourist, enjoy your time but behave yourself.

• If you come from a place where people spit on the ground all the time or throw their trash anywhere, or some weird habits, well this don't work very well here. Don't be gross.

• You might not speack french, but knowing a few words will get you a long way.

Long story short : In Rome do as the Romans.

This advice just work in every city you'll ever be. If you can't blend in Paris, which really see its fair share of oddities, it means you're just doing something wrong. Or maybe you just fancied it too much, it's 10 millions people city, people work here.

Coming from Paris, I've spent some time in London, NYC, Sydney, Berlin. In 24h I knew what I could do and what I shouldn't. All the big cities are pretty much the same really.