In order to become truly proficient at a language, there are several things you should be doing. Attending a foreign language class can help you practice your speaking; this is why we focus on this area at inlingua. It is not enough, however, to attend class or read a book. You have to spend hours working on the language at home.
The question is what you should choose to practice, particularly if you don’t have a lot of time to dedicate to your studies. If your level is A1 or A2, you might want to spend more time studying grammar and reading at home. If your level is higher, however, you should probably practice your skills in listening because after you’ve learned a great deal of grammar, your level of grammar, writing and reading tends to be much higher than your level of listening. Many students fail official exams only because their listening score is too low to pass.
The problem is finding time to practice your listening. My suggestion is to insert the activity in all the free time that you have. When you drive, clean, walk and work out, you could listen to something in English, rather than music. Although listening to music in English can be helpful, remember that official exams won’t ask you to understand a song. They typically play some kind of conversation, lecture, discussion or interview.