This kind of question is rather broad and difficult to answer, because "fluency" is subjective and dependent mainly on each person. There are many ways you can go about improving your fluency, such as reading out loud, practicing what you know in conversation, talking to yourself in Japanese, etc. There is no one "right" way to go about it. It simply depends on how you like to learn and how you learn the quickest. Once you figure that out, you'll be able to learn more efficiently.