I agree with maxiewawa, just want to add a few points...
1. my opinion is, that if you want to learn japanese seriously you will someday get to the point where you have to learn Kanji. It's often a help to see how the words are mixed together not to speak of the many same sounding words. These things become so much clearer if you know the Kanji. I also thought I could avoid Kanji, but thats not satisfying. The more you get into the japanese learning thing the more you'll get confronted with the written language (e.g. internet sites, chatrooms, games etc...).
2. additionally to flashcards was writing the thing that helped me (its the same with Katakana and Kanji) - try to write the signs again and again (and take care about the stroke order).
3. Hiragana AND Katakana are absolutely necessary. There's no more to add
4. If you watch subbed anime you will surely catch a few words. (Especially the words for emotions^^) Thats good for the beginning, but you wont learn japanese from anime alone. In my opinion anime is a good way to get a feeling for the spoken language. But be aware thats a very informal and not usually spoken language (this goes for Naruto, there are also anime out there with a very polite language). I guess/hope no Japanese will shout dattebayo in every 2nd sentence
The best way is to go with the lessons here (and maybe a few books) and then watch anime - you will be glad if you recognize the words you just learned here in your next episode.
greetings
Kageri
(uhm, and english is not my native language - in case something sounds strange...)