First off I bought myself a self study language course.
Take Off in Japanese by Oxford University Press.
I think its a good course and good value.
My goal was one lesson a week but this slipped.
Study
I try to do 20 mins a day. (Not always successful with this goal. But little and often was the standard when I was at school)
I listen to language tapes when walking to work and talk along with them. (Its early enough that there’s no-one around to find it strange. Besides no-one pays attention now that hands free mobiles means there are lots of people talking to themselves in the street.)
Every so often I review what I learned previously and it makes more sense and is easier the second, third, forth time.....
Learning Kana.
I had to write them out and say the sound aloud at the same time. The Book—Self Study Kana Workbook by AOTS—I found to be the best of the books I came across. It has model forms, common mistakes and a CD with the sounds and exercises.
Once learned I have to write them out every now and again to keep them learned. (constructive doodling in boring meetings)
A computer program to quiz me on kana was useful. Nuku is a good one for MacOS X.
Having kana before I started a class was a large advantage and I also picked up vocabulary while learning.
I joined a class. It gives me set goals and targets to meet. And help in what I’m doing and someone to try my Japanese out on.
I review before and after the class for it, and try to anticipate what’s coming up so the class is a mix of new and reinforcing what I’ve already read.
To build up a vocabulary I’m starting to use flash cards.
I also keep a notebook of words by theme as well.
Browsing the Internet doesn’t count as study.
Nor does watching Anime.
(well it does sort of sometimes, I have a couple of Ghibli disks with Japanese subtitles that have thought me some things)
I try to associate the kanji with words I learn. (I figure I may as well do it now). If I can, I write them. Repetition seems to be the best way to make them stick.
I also sometimes try to give an internal running commentary. Say the date or time in Japanese to myself, hello, goodbye, thank-you, I’m home, prices, etc. etc. whatever I can.