I think the best thing to do is learning the sounds of the language first. You can try http://japanese.about.com/library/blhiraganaaudio.htm for practicing isolated sounds. After that, it'd be a good idea to practice listening to words and sentences to get a feeling of stress patterns and intonation (how the language flows). Once you can recognize sounds/words and repeat them, you can start listening to audio lessons (e.g.: http://www3.nhk.or.jp/lesson/english/). You can also look for Japanese material that you're interested in, like anime if you're into it. Personally, I wouldn't try to read/write until I can understand spoken Japanese — and speak it properly too. But maybe it's a matter of taste. Once you're reasonably proficient in the spoken language, learn hiragana, katakana and kanjis.