I learned by writing them over and over again and trying to use them as often as possible. However, I think there are better methods. "Remember The Kana" is a great book that uses stories to make remembering each kana easy.

I memorized both Hiragana and Katakana by staring at a chart for about 3 hours.

All these flash cards and cute little games and whatnot are unnecessary.

By using it, simple. Buy a J-Phone or Docomo and experiment :)