While you could learn some basic gammar and volcab from books, web couirces, software etc. You can only really learn the language by living in that country AND forcing yourslef into an environment where the only way to live is to speak the langauge.You will also need to allocate lots of time, and when your brain is fresh not tired.
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In fact my French has got worse in the last year as I am simply too busy to utter a word most days - at the same time my English has definitely got worse as well, something to be careful about if you plunge yourself into non-anglophones.
Agreed..