A structured class setting works pretty well for most people; Before that, I would recommend getting a good beginner's book or use one of the many links on these boards to sites (start off learning hiragana and katakana, there are plenty of sites for that).
If you pursue this to an advanced level, you'll probably be relying more on your own motivation to learn vocabulary and writing styles particular to your field of study. The writing style of journalism in Japanese is very different from normal writing styles, which are very different from speaking styles (which is where most classes start). There are many advanced classes that concentrate solely just on reading the newspaper.