I began Russian in college. I picked it more or less at random from the course catalog to fulfill my school's language requirement. My only criteria was that I didn't want to study a Romance language, since that was all that was offered at my high school. I did pretty well my first two semesters then did an intensive summer program at another university, at which point I had covered pretty much all of the grammar and had built up a decent vocabulary of basic words.
Once a person is at this level in a language, it is vital for self study to completely eclipse coursework in terms of volume. The reason for this is you simply have to see words and grammar constructs in hundreds if not thousands of different scenarios in order to build up enough repetition so that they feel natural. I spent a lot of time researching different language learning methods.
My primary method for this was audiobooks with the corresponding text . I would find an audiobook for a story I knew well (Harry Potter to start) and I would read and follow along. And this is the important part: I did not stop the audiobook under any circumstances during the session. It is more important to be exposed to more words and sentences than to stop and look up every unknown word. Given a sufficient base of grammar and vocabulary, words can be learned from context (while reading Harry Potter I figured out the words for wand (палочка - palochka), hut (хижина - khizhena) and toad (жаба - zhaba) entirely from context. The words I didn't figure out didn't bother me— I knew roughly what was going on. This tolerance for ambiguity helped me not get overwhelmed. My philosophy was "if a word is important I'll see it again."
I further developed this study method by downloading a pop up dictionary for my browser while listening and reading. This allowed me to learn a huge number of words without ever having to stop and look things up (a significant source of friction ) or even write things down. It was interesting to see how some words I could learn after seeing them once or twice and others required countless repetitions before they sank in. I was able to learn words that often only appear in writing such as ones used for literary emphasis ("he rushed across the street" instead of "he ran across the street"), words for sounds ("clang", "crash"), plant names ("reed", "willow"), and geographical formations ("ridge", "ravine", "embankment").
A person's written vocabulary is typically much larger than their spoken vocabulary, so relying on sources such as television/movies/conversations with native speakers is insufficient to develop native-like mastery of a language. And audiobooks have significantly more words spoken per minute than a movie or TV show.
Contrary to popular opinion, studying abroad is not necessary to achieve fluency. That said, I highly recommend it, because it helped me in many ways. I had a great time that was greatly enhanced by the fact that I was already at the point of understanding most of what was spoken to me. This allowed me to have real conversations that weren't constantly interrupted by "sorry can you repeat that" and "sorry I don't understand." or worse, nodding along pretending to understand. Learning to speak fluently is hard enough as it is, so do yourself a favor and get your comprehension as high as possible before traveling if at all possible.
The study method described above was heavily influenced by the ideas described here.