Firstly, I’d like to point out a fascinating thread over at Reddit discussing this exact question that has a lot of interesting responses and turned into a great discussion: How did you become fluent in another language?
Secondly, if you haven’t joined the language-learning subreddit on that site, you should, it’s worth joining just for that alone (and the people on reddit are awesome for the most part, by the way): /r/LanguageLearning
Thirdly, if YOU have ever learned another language to fluency (we’ll say “conversational fluency”, basically just to the point where you could readily converse with the natives about whatever) then I’d like to hear from you in the comments about how you managed to do that!
That’s it! Short post today – I’m working on the upcoming Shakira post, 3rd in the series, plus I’ve got an article on verbal manners in Spanish in the works, those should be out within the next week or two.