In preparation for your next trip to France, here are a few things you can do Stateside to get yourself ready. Following this prescription may get you some funny looks at home, but you will be infinitely more at ease once you arrive in the Hexagon.
A week or so before you leave, begin with the simple step of saying a greeting every time you walk into a store, the post office, a café, or the bank. When you enter the establishment, you need to do a lightning quick assessment of who is currently in the place and make the appropriate verbal adjustments. Here are your potential scenarios:
Situation 1: The only person in the place is a man. You say (invariably) "Hello, Sir."*
Situation 2: The only person in the place is a woman. You say (invariably) "Hello, my lady."
Situation 3: There are two or more men in the place, but no women. You say (invariably) "Hello, gentlemen."
Situation 4: There are two or more women in the place, but no men. You say (invariably) "Hello, my ladies."
Situation 5: There is one man and one woman in the place. You say (invariably) "Hello, my lady, Sir."
Situation 6: There are two or more of each gender in the place. You say (invariably) "Hello, ladies and gentlemen."
Situation 7: There are 643 women and one man (or the opposite). You say (invariably) "Hello, ladies, Sir." or "Hello, my lady, gentlemen."
It is extremely important not to get creative or cute in any of the above. The only acceptable variation is to omit the "hello" and simply say "My lady, gentlemen" upon entering. Flaunting your diverse vocabulary is an absolute no-no, so don't even think about saying, "Hi there!" or "Hey" or "What's happening?" or, God forbid, "Oh, I just saw your window display and had to come inside to check it out!" In France, you will find that all of these are grounds for immediate deportation for Deviation From The Script.
As you prepare to depart the establishment, take a renewed census of the place (if the man has left, you will need to adjust accordingly) and say (invariably) "Goodbye, my lady/Sir/ladies and gentlemen, etc." Again, this is neither the time nor place to show off your lexicon. "See ya, Toodle-oo, Later Alligator, Take care, Have a good one" are all off limits.
It is exceedingly important that you do this upon entering and exiting every establishment, whether it is the dentist's office, the funeral parlor, the supermarket, or the mechanic's. Note that even if you don't think anyone can hear (or cares about) your greeting or your goodbye (as can be the case when entering Wal-Mart or its French equivalent), it is still essential to say them out loud. While mumbling or swallowing half your words is perfectly acceptable, remaining silent is the hallmark of the cretin.
As you get comfortable with these easy beginner steps, you are ready for Phase Two. At a restaurant, after you have offered the customary greeting, you can, as you are being shown to your table, wish the diners you pass a bon appétit. It is strongly encouraged that you time this so you only need to say it once. As such, you should begin your "bon" as you are already passing the first table, concluding the "appétit" as you pass a second or third table, loud enough that the first table will hear you and the last table will catch the end of your good wishes, but NOT loud enough for someone 14 inches away to hear. It is tricky, but you'll get there.
If, as you leave a restaurant, other diners are just beginning, you are more than welcome to wish them the same bon appétit. Naturally, because you are "properly brought up," you will note that, if said diners are enjoying cheese, dessert, or coffee, they have already concluded the bulk of their meal, so "bon appétit" will be not only misplaced, but also a display of your cultural poverty that is as subtle as a siren.
If you think you may have some time in France away from strictly tourist locations, where you may be invited to social gatherings hosted by French people say, at the opening of an art show, a restaurant, or someone's house, you can begin getting ready right now.
Let's imagine you have been invited to your American friend's house for a party where 30 guests are expected. You arrive when approximately half the guests are already assembled. In preparation for your trip, make it a point to greet each and every guest personally before doing anything else.^ No getting a drink, no nibbling from the bowl of chips, no conversations of substance or length until you have greeted every guest in attendance. It is entirely appropriate to interrupt whatever discussions these guests are having to exchange these simple pleasantries (without which, we are really just cavemen, aren't we?). Once you have completed your rounds, get yourself a drink and engage in normal conversation with the other guests. Make a point of judging the guests who arrive after you, whose woeful lack of upbringing has resulted in their shameful and selfish behavior (snagging a drink before greeting you, telling stories about their kids before greeting you, eating before greeting you, etc.). It is OK to say, in a theater whisper, that these people are barbarians. It is good practice for France.
Naturally, the time will come to leave the gathering at some point. It is essential, as part of your training, that you budget approximately 30 minutes for your departure, or one minute per guest. Under no circumstances should you thank the host/ess and give a general wave to the crowd before heading out the door. Doing so is surely the sign of an uncivilized person. No, the situation of course requires you to say a personal goodbye to each guest assembled. Here, conversations can linger (everyone having had some wine by now), and exhibiting any sort of urgency will be frowned upon during your trip in France, so practice taking your time and doing the rounds. Once you have said your goodbyes to everyone, make a last stop at the host/ess for a final formal expression of gratitude.
While you may hesitate to practice these techniques with your friends and family for fear of mockery, remember that it is infinitely preferable to be teased by those who know and love you than to be publicly shamed and humiliated by the French, the most cultured, refined, and sophisticated people to ever walk planet Earth. (Just ask them; they'll swear it is true.)
So get to work!
*When in France, you will of course have to say these in French: Bonjour/Au revoir, Madame/Monsieur/Mesdames/Messieurs.
^You may be wondering about les bises, those little kisses French people give each other. Please be reminded that this is an introductory lesson, not graduate school. You're not ready.