First off, if you walk into a MacDonalds in the United States, go up to the counter, and say "Big Mac and fries, please," everyone will think you are very polite, because you said "please." In Martinique (anywhere French, really) they will think you are very rude, because you did not say hello first. So, always, ALWAYS start with "bonjour." Do that and you will find that people are much more receptive to you.

Second, do try to learn a few phrases. Honestly, if you walk into any shop, restaurant, or hotel and can say to them (in French, of course) "Hello. I don't speak French very well. Can you help me?" 99% of the time you will find that they are perfectly happy to speak English. Of course, learning how to say "hello," "goodbye," "please," and "thank you" in the language of the country you are planning to visit is just the minimum that you should do.

Contrary to those who say that the French are rude and unpleasant, and don't like Americans, my experience has always been exactly the opposite. I have always found them friendly, helpful, and accommodating. Indeed, the first time I visited France I was kind of shocked at how friendly and helpful everyone was, because of the stories I had heard. If you make just a small effort to understand and adapt to their culture, I think you will find them just as pleasant as I always have.