Here it is :
In general,the best method would be living in country in which that language is dominant, to execute everyday tasks using that language. If you interested in particular language, say Russian, - OK!! Go to Russia ! And try make living over there.Yet try to find Russian community close to your city and go there! I'm sure they will be glad to help you.... At least you have to exercise language with native speaker - there is NO! other way to make it BEST! You're asking about the BEST WAY, don't you ? THAT'S THE BEST !
In my turn, I would be glad to help you would you chose that method - I'm native Russian :-))
Local time: 09:39
Native speaker of: Russian
PRO pts in pair: 92