In my experience the best way to learn a language is to use a book and read/write enough to have a basic hang of the language. Once you have the basics down, fo

In my experience the best way to learn a language is to use a book and read/write enough to have a basic hang of the language. Once you have the basics down, force yourself to start thinking in that language. Make it a game: each time you get an entire sentence of your thought process correct in that language reward yourself. If you make a mistake punish yourself. The disadvantage to this method is you need a lot of discipline to keep constantly forcing yourself to think in a new language, and you will spend a lot more time when thinking.