[ThirdSight]

Like chryuop said, learn Kana. Just Hiragana and Katakana at first; roll slowly into Kanji with both of those well under your belt.

Your friend's right, start learning the formal way to say sentences. Once you can do that, just remove a few formal words and you'll be speaking informally (not so cut and dry, but it's easier than learning informal to formal).

I always recommend Berlitz for those self teaching themselves the language, it's a great computer program. Look into it.

Those are just some tips to get you off in the right direction, the rest is up to you!