Best way to learn Japanese?

I'm going to study abroad in Japan in a couple of years, so I decided to start the language early. I'd like to know the best way to learn before I can go there. I don't mind how hard it is, as long as it works.
Thanks!

I would recommend one of two options, either find a school or get a teach-yourself book and a tutor.

Personally I like to study at my own rate, whether it's faster or slower than other people, so I went for a book which I could study at my own pace. I use the "Japanese for Busy People" books which I think are excellent, although I've also heard that the "Genki" series is very good.
These courses teach everything from grammar and vocab to Kanji, but they introduce things at a very well judged pace so you don't feel overwhelmed.

I would recommend getting a tutor as soon as you start studying though. It doesn't have to be an expensive person who's a qualified teacher. My tutor is a Japanese girl who's at university here, I see once a week, and she allows me to ask questions (can't ask a book!) and she corrects my mistakes before they become ingrained.

This worked for me, and I now see some more people for regular language exchanges. I still make loads of mistakes but once I learnt to have fun with that it's really good and I'm getting better all the time.

I would steer clear of the "miracle methods" which promise you can learn all the kanji, or thousands of words of vocab in a few months. Learning a language is a long process, expect it to take years and you won't be disappointed. The good bit is you'll make much faster progress once you're there!

If you are looking to do it on your own or from home, Japanese Mastery Method is one of the better online courses (not free, but seems you get what you pay for out there). They have a starter Kanji video course that is free though. It's pretty cool.

http://japanesemasterymethod.com/learn-kanji

If you do get a tutor, make sure they are teaching you particles and verb endings via pattern recognition, and not rules.

If you do get a tutor make sure they are not giving you lists of words, but are having you realize the meaning on your own based on context. This will help you learn faster.

Learn Hiragana and Katakana right-away. They are easy and don't take long.

If you have a smartphone or tablet, I can highly recommend Human Japanese (available for most mobile and not-mobile platforms). Personally I have never spent 10 euros so well.

It will teach you the kana's, lots of words, grammer, and much more and all that explained in crystal clear English, written by a man who's native language is English.

(no affiliation :P)

Watch YouTube
ex)http://youtu.be/yaoKzYJwfXc

Join Lang-8 or similar SNS.

Also J-anime with fansub well.