Over the course of time, I have found that I must do to become competent in a foreign language is to immediately use what I have learned. I have spent many years perfecting my Japanese speaking ability and although it still needs work, I can now say with a high degree of confidence that I can speak Japanese.
For those who do not live in a country where the language is spoken by the majority of the population, I suggest seeking out places where the language is used. In my case, it was a Japanese supermarket chain called Mitsuwa Marketplace. Here, I was able to immerse myself in Japanese and doing so did wonders for my speaking, comprehension, and reading abilities. Whereas many of my fellow students would forget everything right after an exam, I was able to build on what I had learned thus reaching a higher degree of fluency.
After becoming able to converse in a foreign language, one should focus on language maintenance. It would be a shame to forget what one has spent so much time and effort trying to learn. I am constantly using Japanese with friends, watching Japanese T.V. shows, listening to Japanese music, etc. Basically, I view any kind of exposure to the language as a plus. Living in Korea affords one many opportunities for studying Japanese in the form of language schools, Japanese language channels, and the proximity to Japan itself.
If one has trouble finding the motivation to study, I suggest looking for something that interests you that you would need the language for. This could be anything from wanting to understand the meanings of the songs that you sing to wanting to hang out with the locals and not be left out on the loop when someone tells a joke. At one point, my motivation was Japanese video games. Most of my friends were content to just play the ones that would reach the States but I needed more. I wanted to learn Japanese so much that if my elementary school would have offered it, I would have taken Japanese then but no such luck. Once being exposed to the culture, I became interested in other aspects of Japan and through Japan, I became interested in other Asian countries. I doubt I’d be in Korea at the moment if it were not for my wanting to play Japanese video games as a child. I guess having the proper motivation can open many doors in the future.
So, three things that I think are especially pertinent to language study are using what you have learned, maintaining what you know, and finding the right motivation to get yourself started. These three things, along with others, will take you far when you decide to dive into a foreign language.