The premiere Korean language company- Talk to Me in Korean- suggests one thing to do to improve the study of Korean- use a journal. This can be applied to learning any language.
They suggest that you write every day in your journal using the language skills that you wish to improve. Use subject matter that is meaningful and important to you and you are more likely to continue the practice. For instance, if you enjoy writing about family or a friends, that is what you write about in the language that you are learning.
Watch the video where a Talk to Me in Korean host explains the method on Youtube: Do This One Thing to Keep Improving Your Korean.
Peace,
Deborah