Learn the Culture
The first thing you want to do is to know about the culture of Japan. Languages have a strong relationship with the local culture and traditions and once you have understood the customs, you can understand much more about the language than a person who is unaware of the culture.
Go to your local library and grab some books and videos and start learning from them. This will get you an idea of the basics of the language which is very important. You can practice the speech with the help of the videos. In order to increase you understanding, you can watch movies in Japanese which will provide you with an opportunity to understand more of the language.
Hang Around with Japanese
You can further hone your skills in the language by hanging around with those who speak it. You can do this at your university or office and also can go to Japanese restaurants and make a few buddies who are willing to help. Nothing beats the practice that will be attained through this route and you should be learning it faster than any other way.
Try to get some advanced level books and videos on the grammar. Generally, grammar is the toughest part in any language and must be able to understand it to some extent to be able to speak the language well. Also make sure that you increase your vocabulary on a constant basis.