For any language, reading, writing, listening, talking with natives, watching TV or something are the best way to improve languages. But I think firstly the most important is what kind of things you are interested in Japan such as food, movie, anime, culture, fashion, history, people and so on, and then find out something related with it. It is also good way to take a Japanese language test to focus on. I recommend you the following besides the grammar and writing Notebook. ※ Rent a Japanese DVD film whatever you like, from shops, which have Japanese caption/subtitles. (Many learners at the beginning find Japanese anime is fun and easy way to get common conversation better than movies and dramas, and then start to learn the language more. So I think anime is not so bad. Just one of the option.) The contents of DVD films are usually better than TV. The DVD film you can stop and repeat many times you want. ※ Find Japanese books which must have ふりがな/ルビ(hiragana printed beside each kanji). Although those are for Japanese kids, there are still a couple of books with ふりがな/ルビfor adults. The books are much useful to get the proper Japanese language. ※ Talk with natives who live in your city and via voice chat or video chat with your friends on italki. But I suppose it is better not to ask many grammar questions to them who are not usually the specialist. 　 Just enjoy conversation and sharing the time with the native. (I can chat with you for around 15 to 30 minutes sometimes on weekend if you like.) ※ Take professional lessons. あれ、danは日本語で質問しているので、日本語で書くべきだったね。

well, it's really difficult to answer this questions. but without doubt, watching japanese tv and listing to japanese music must be helpful for you. i know many conversations in TV are not formal, and sometimes too casual, but those conversations are our real conversations. So even if the grammar in that conversation is not correct, i think, you don't need to care so much. just ask me if you can't understand the meaning of the conversation ;) Kota