Apart from learning the basics and putting in lots of quality study time I recommend these two methods

1. Immerse yourself in anything Japanese. Learn as much as you can about the culture and social customs of Japan. Get involved with Japanese clubs and the like. You will be able to make friends and pick up a lot of real Japanese this way.

2. Watch Japanese dramas. This helped my Japanese greatly. I would watch an episode of a drama several time on video. I would pause and repeat lines and work out much of the language from the context of the scene in the drama. It worked wonders for me.

Also, interactive websites that have screen capture videos that explain the language are also good.

http://speakjapanesefluently.com/
http://readjapanesefast.com/