Learning French in France is far and away the best way to pick up that language, and if you have any doubt about that, take a look at me. For years and years, I studied the French language, but until I took a course to learn French in France, I never really got anywhere.
You can take as many French courses as you want to in high school and college, but they will only get you so far. If you want to study a foreign language and really learn it, the bottom line is that you have to go to the place where that language is spoken natively, or you will never master it.
There are many reasons for this, but I will just go through the very most important one here. One of them is simply that it is easier to learn a language when you need it to survive. If you try to learn French in America, you only really work on your French skills during the time that you are doing homework or in class. Even if you only speak French when you are in class, that is only a few hours a week at most, much less time than if you were to learn French in France.
When you are learning French in France, you get to pick it up all week the time and not just for a few hours a day. You will not only learn French in France from your classes, but also talk with strangers on the street, from looking at street signs, or buying food. In short, everything that you do there will help you learn French in France, so it is easy to see why it is so much better of an option than continuing to study it in America, or some other non French speaking country.
If you want to learn French in France, the best way to do it is through a foreign language program. Although there are thousands of programs that maintain to be able to teach you French in France, they vary in quality, and only a few of them are really good.
It is important to do thorough research and not just go on the first learn French in France program that you see, as you might end up having a very bad time at it. You might even fail to learn French in France in the process. But a good program could just be the adventure of a lifetime.