Not sure if you are still on the site or forgot about learning japanese already, but here are my suggestions:
lessons with teacher - he/she can always answer your grammar questions which might be hard to find out on your own (unless you ask on a site like that

), it also motivates you, if that's a problem. It's just easier i guess, cause you don't have to find out everything on you own, but if you're motivated enough (and keep this motivation for loooong time) then you could do it without lessonss.
books - duh
music/anime/games etc - good way to immerse yourself in japanese, hear a lot of it etc. Not a great way to learn only from it but it's a nice bonus
podcasts - listening to japanese text, then translated and explained. Its nice because you can do it on your way to work or school, or on a trip or wherever. Not sure if i can recommend a site here... but im using japanesepod101. Pretty nice.
Anki/other flashcards programs - it's a great way to learn kanji in my opinion. Its basically flashcard program, that lets you review and learn kanji or whole sentences or whatever you choose (from many different courses that are free to download). You set how many you want a day, for example 5, and you learn those 5 everyday and review those from previous days. If you master it enough they appear less often. Repetition is very important, because its easy to forget older ones or more complicated ones. Im currently doing japanese sentences, so i learn both kanji in sentences and meaning of words (first i see sentence in kanji, then i see how you read it - with furigana and translation).
Ok thats all i came up with for now. I personally am going to class with small group, learning kanji/words everyday on anki and listening to japanese podcast from time to time as i mentioned.