Here are some useful phrases to get you started:

(1)     In France , a simple hello can be the difference between being treated with courtesy and being snubbed in a restaurant or store.  Never neglect to say hello, and add the appropriate title to be even more polite.

(2)     Say "pardon" when trying to get by someone, or bumping into someone...

(3)  "Au revoir" ( until  see each other again ) is the preferred way to say goodbye, even to strangers you will never see again because "Adieu," literal translation meaning " to God," if misused can be seen as an insult ( i.e. You don't ever want to see that person alive again). À tout à l'heure is a more familiar way to say goodbye, but can be used with strangers if you know for a fact you're going to see them later on.

In general, the stress should be placed on the last syllable of the word, and the last word of the phrase.  Also, in general, the "s", or "es" at the end of a word is not pronounced unless the word after it starts with a vowel. For example: Nous allons ( We go), the "s" at the end of "nous" would be dragged out into the "a" of "allons" making a "z" sound, but notice how the "s" at the end of  "allons" is not pronounced. ( Nooz ah-lohn). Why? Because it sounds weird if you don't, like a hiccup, or an extra breath in your speech where you don't need it. The French language is all about words flowing gracefully.

If you want to speak in English, think to speak slowly: Generally, French people don't speak English very well. And the English taught in France is the UK prononciation. For a French speaker who understand a little UK English, it is an added difficulty to understand American English. In the larger cities, you are more likely to find people who would understand some English than you are if you went to smaller villages.

Don't shout!  If they don't understand your English, shouting will not help. Also, there's a concept of a smaller "personal space" that may take some getting used to. Typically Americans need about 3 ft of personal space to feel comfortable when talking to someone. Of course this varies with familiarity. In many other countries, including France, that space is smaller and it is seen as being rude if you back up or jump back suddenly.

When shopping or ordering, it is helpful to know that the French begin counting with their thumbs, so an American holding up their first finger for "one" may appear to be signalling "two."