Hey. I also decided to learn japanese about 9 months ago, from that time I am learning it without any teacher. I have some thoughts about it:
On internet you can find a lot of necessary stuff to help you learn it.I started with kanadian tv program called "Let's learn japanese"(I think it's really good for start, they teach you basics and also a pronounciation because it was made by japanese natives) and also I learned from different sources. To learn it efficialy I need a book so I bought Japanese grammar of Maho Ikushima and guys from university in my country, it is really hard to read and what is there written about pronounciation I would say it's almost imposible to learn from book but for this I used anime and movies (I know that in anime they don't speak like in usual life but I hope it doesn't differ either).Also these books are really good if it is about grammar. So for learning grammar I am using mainly these books and at beginning Lets learn japanese. If it is about writing I started with hiragana and katagana afcourse then I stopped for some time (I intended to learn japanese on the communitive level in one year because I found really interesting job offer, I thought I can manage it but not with learning kanji, there is too much of them), ...after some time I was learning only grammar and vocabulary that job offer vanished and I decided to start with kanji. I started with programm "yokozuna" and new kanji I searched in programm "JWPCE" and I writed down in my notebook words which consisted of this kanji(not every afcourse but those I thought will be useful in future) yokozuna had 3 levels only so I am now using
Kanji Land Lesson archives Grade 4 . I am not trying to memorize kanji at once, I am trying to get familiar with it, then while reading grammar book there are sentences in kanji also every day I read some of my kanji notebooks. Learning kanji is really fun, you starting to realize what is the orign of words you knew and learn a lot more interesting(my favourite is hadakamairi - going to the shrine naked in the witer
) So after 9 month this is where I got...I think I have vast vocabulary, I understend most of grammar, I am familiar with about 700 kanji I can watch some anime or movies without subtitles. Although I am not really good with using grammar yet, it will take some time and teacher or living in japan would be very helpful. Oh yeah, I am spending at least 2 hours daily on japanese, sometimes it is much more. For these 9 month I didn;t have a break. I am sure you can learn it by your own but it will be dificult and can take more time than with teacher, also with teacher and curses you can't do it on very high pace. So if you won't spend on it a lot of time I suggest finding tutor or going for lectures. Good luck!
Damn, I wrote so much and now Iam late for tenis match