@schacon Interesting post. I agree that language-learning is more of a marathon than a sprint. As someone who speaks several languages[1], it was interesting to read about your perception of how polyglots learn languages. You picked up on some good things (flashcards and these days spaced repetition learning programs since vocab is critical, multiple different tools and books, online tutors) but you didn't mention a characteristic that most polyglots I know share[2]: an excellent foundation in the grammar of their own language, and the inclination to spend the time necessary to build a good foundation in the grammar of whatever language they are learning. I'm sure there are exceptions to this rule, but it seems to be enough of a trend that it's worth mentioning.

Some people promote the idea of learning a language "naturally" through an immersive environment. Although immersing yourself in the language is critical once you've picked up a strong foundation, I've personally known very few people who have learned a language to near-native fluency as an adult by simply jumping into a new language environment. Kids do this all the time, but the way most adults successfully learn a new language is different from the way children do it. I've watched some people waste a lot of time trying to speak to native speakers of a language they're learning without having any kind of foundation in vocabulary and grammar. They would have done well to spend at least a portion of that time picking up a basic vocab through flashcards and learning grammar fundamentals of the foreign language in question.

And although I'm sure there are exceptions to this rule, most polyglots I know are fascinated by grammar, in addition to having a strong interest in phonology and speech/accents.

So to anyone who has tried and failed to learn a foreign language as an adult and is thinking of giving it another try, I recommend picking up both a review book on the grammar of their native language, as well as a basic but complete grammar of the language they are targeting. Spend some time with these books along with Anki and the language-learning apps, and then go out and immerse yourself in another language environment, either through online language communities, or living/traveling abroad.

And one last type for new language learners: be sure to study idioms and phrases when you use Anki or whatever flashcard program, and not just simple words. Having a good stock of idioms is critical to fluent conversation.

1. At one time, fully fluent in 4 languages, now 2 are rusty but I'm picking them and another back up. I've also enjoyed an intermediate level of fluency in an additional 5-6 languages at one time or another. (I've also worked as a professional interpreter (2 years) and translator (10 years))

2. The only exceptions to this rule have been people who have learned 3-4 languages as children, but even they have a much better knowledge of grammar than most Americans I know.