Stilton: The best way is to go to a non english speaking country and refuse to speak anything but the native language. Embarrassing and awkward to begin with, but you're supposed to pick it up fairly rapidly if you want to eat and find the toilet. It makes sense. Other than that its just down to repetition, doing it over and over until you have the rudiments and then go from there.
ryuutane: What Stilton says is only true.
Unfortunately there is a conspiracy which the English speaking people know little about, namely all the other nations try to speak English so that it would be impossible to learn foreign languages. Well, the French are a little recalcitrant, but we'll get them on board.
So you should go first to france and then to other countrys insisting of being french ;-)