Recently, a friend and highly proficient speaker of English posted a video of herself and her two sons, reading and responding to Where the Wild Things Are. There were many things to appreciate about the video, but the thing that I found most significant was the effect of repetition. Clearly, the two boys had heard the story many, many times, and their mom had repeated the phrases in certain ways to help them remember. So finally, they were able to say the story themselves.
It's easy to forget that this is the way we learned a huge amount of language when we were growing up: simple repetition. I'm not talking about just memorization, but the kind of creative repetition that you really learn from, sometimes with pictures or songs to help you. You see kids doing this all the time, like repeating the announcements on the metro, or singing the theme song of the TV show they've just watched.
As adults, the same process can be very useful to us. For example, we hear many expressions over and over again, and we internalize them well, like "How are you?"
I think it's possible to extend the concept of repetition to reading, listening, or watching a film, video, or TV series, because the writer or speaker will repeat words, expressions, and other structures, and you will learn from these. For example, a blog can be a great source of creative repetition, because the writing style is usually consistent, but the topic is always changing. This way, by regularly reading the blog posts, you have both the value of repetition and the opportunity to learn new words.
Sometimes I think that adults feel like they should learn a language quickly, without having to practice. If we reflect on the way children learn their native language(s), however, I think it's clear that repetition is important, and if we take the time to do it, we'll learn better.