100% the pimsleur audio course is the best way, even better than immersion (I've done both). It's based on a method that they used to use to teach diplomats as fast as possible.
Not sure if I still have discs
Pimsleur is garbage for learning a language. Make a friend who is a native speaker of the language you want to learn, and ban yourself from using English with them. Get them to describe stuff in their language, and over time you'll learn more and more. It's how I learned my husband's native language.
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