Although some aspects of culture are the same, it can be quite a shock when you get there.
To start with the food is rather different than what is commonly eaten in the USA.There are relatively few quick food outlets.The French like to have proper meals at the table and they do not snack in between meals. You may have heard that they eat snails and frogs legs, but these are actually rarely served .
In restaurants and cafés, by law, the prices that you are charged are inclusive of taxes and tips, though in hotels it is still customary to give a tip to the person who carried the luggage to your room for you or the person who gets you a taxi at the hotel door. With regard to tipping other people, you tip usherettes, taxi drivers, the ladies that keep your coat at a public venue or those who look after public conveniences.You also tip the person who took you on a guided tour of a castle or other place of interest.
Good manners are world wide but the French are particularly sensitive about these.They are private people and have different rules of behaviour for people within their social circle and those who are not. Although they are generally polite in all dealings, it is only with their close friends and family that they are free to be themselves and be more familiar. They usually are courteous towards strangers but somewhat reserved when you just meet them and may seem distant to Americans who tend to be more demonstrative and loud.
The handshake is a common form of greeting. Friends may greet each other by lightly kissing on the cheeks, once on the left cheek and once on the right cheek (in Paris 3 times: left, right, left).
First names are reserved for family and close friends. Wait until invited before using someone's first name, and call them "vous" unless they tell you to use "tu".
You are expected to say 'bonjour' or 'bonsoir' (good morning and good evening) with the honorific title Monsieur or Madame when entering a shop and 'au revoir' (good-bye) when leaving. People smile less than Americans when meeting strangers.
If you are a guest in a French household for a meal: arrive on time. If delayed, telephone to explain you have been detained. If invited to a dinner party send or take some flowers or chocolates. Florists are open on Sunday mornings, by the way, and so are patissiers and chocolatiers.
Dress well. The French are fashion conscious and their version of casual is not as relaxed as in many western countries. Some clothing worn by American or British people immediately makes them identifiable as tourists. A French girl would not go round a town in shorts or a pelmet skirt unless she was at the seaside in the summer.
Men wear classic trousers, not the varieties of pants that one sees in America, though younger people do wear jeans and tee-shirts, but not the distressed versions.
Table manners are continental -- the fork is held in the left hand and the knife in the right while eating.
A guest should wait to be be directed to a particular seat at the table and not start eating until the hostess says "bon appetit" and starts eating herself.
If you are faced with an array of cutlery you start from the outside for the first course and progress inwards for each course that follows. Soup is often served as a starter. Bread is always presented at every meal and you put it on the tablecloth to the left of your plate, not on a side plate. Cheese comes before dessert, by the way, and is eaten with bread, not with biscuits.
If you have not finished eating, cross your knife and fork on your plate with the fork over the knife. Do not rest your elbows on the table, although your hands should be visible and not in your lap. Finish everything on your plate. Do not cut salad with a knife and fork. Fold the lettuce on to your fork. Peel and slice fruit before eating it.
Each individual is provided with a napkin for main meals.
Breakfast usually consists of bread, butter and jam with coffee or chocolate to drink.
For other meals, in most restaurants your food will come ready plated, but in very smart restaurant a waiter may serve you. In a house where you are a guest you usually help yourself to dishes that are passed round unless there is a servant dishing it out. Always think of others if you are helping yourself and do not overload your plate: it is bad mannered and you may deprive someone else. French portions are smaller than in America, though they may be more courses to eat.
Do not leave the table in the course of a meal unless in an emergency.
Offer to help your hosts but do not be surprised if they refuse: you are a guest and as such are not expected to clear the table or do the washing up.
If you are staying with a family, bedrooms are "private territory". One should not go and "explore" the house without being invited to do so, and one shoud never go and look in other people's cupboards or read things addressed to others.
The bathrooom is just that, for other needs it is "les toilettes" or le WC (pronounced "le dooble vay say"). In some hotels or private bathrooms you may find a strange basin shaped a bit like a toilet but with taps. It is a "bidet" and used to wash one's intimate parts. In more remote areas you may find that some public toilets are still the "Turkish" sort of lavatory where you squat rather than sit. Beware the flush as it is very poweful and will wet your shoes. Some towns have individual cabins that you pay through a slot to enter and these are super clean as everything is automatically washed after each visitor.
By the way it is untrue that the French are dirty and unhygienic.
French people do not queue, and catching a bus can be quite anarchic, thought they are courteous enough to let old people or women with young children on first. There are seats in public transports reserved for incapacitated persons or pregnant ladies and if you are sitting in one of those you are expected to give your seat up if you are asked by someone like that who has got on after you.
Some shops are more specialised than in the USA, so you may find a bread shop that sells exclusively bread but not cakes, butchers that sell a special kind of meat only. Confiseurs sell hand made chocolates and iced fruit but not industrial brands. Chemists sell medicines and items of personal hygiene but not hair brushes, cosmetics or perfumes. You can buy stamps from post offices or tobacconists only.
When meeting people be smiling and pleasant but not over effusive or loud and people will think you are beautifully mannered. You can be more relaxed with people of the younger generation who are less fussy about traditions and étiquette.
Wherever you go , you will find interesting or beautiful things to see or visit. There is so much culture that you really will be dazzled. You will find most people are nice, except perhaps in the streets of Paris where people are always in a hurry and are fed up of being accosted by strangers asking for directions or help, or beggars. Taxi drivers live on their nerves and can be rude.
If you are in Paris, watch your bag and keep your valuables safe. Like in all capitals there are pickpockets and opportunists preying on tourists and the unwary. If anyone approaches you trying to sell you something ignore them and go with a firm "Non merci". There are many East Europeans and legal and illegal immigrants that are trying to sell things like jewelry (fake or stolen) or other worthless things.
It is a good idea to learn a few basic greetings and common phrases before you go. The French appreciate people who make an effort to approach them in their own language and one should not assume that eveyone speaks English. You can pick up most of these sentences on various free language websites.
French menus can be quite intricate particularly in smarter restaurants and may lead to misunderstandings, but there is usually someone on the staff who can explain in English what the food consists of, unless you are in a very basic place where recipes are either traditional or local. Poulet de Bresse for instance does not mean "breast of chicken" but indicates the region where it was raised. Look up in advance what most common dishes are called.
Have a great time when you get there!