Kana (Hiragana and Katakana) are a set of syllables and sounds. Kanji are symbols with meanings. First of all, learn hiragana and katakana, no special knowledge is reguired for those, just grab a chart somehow, and possibly something that has stroke order. Even though at first the order might seem weird, follow it. As for kanji. Well you can use the orthodox method, grind, grind, grind, which is proven to work 100%, or get a copy of Heisig's Remembering the Kanji, which many find dodgy. Its up to you. But for now, forget the kanji, build a vocabulary, understanding of grammar, and try to develop a good ear. I dare say you needn't learn hiragana and/or katakana for the first three-five weeks, just stick to romaji, and start writing when you achieved something, that way your determination will not fade away, and you won't become frustrated. This is just a countermeasure, if you have trust in your resolve go ahead and start learning kana, you can even pick up one of those Gordian Knot difficulty "Im-so-pro-cause-i-learnt-kana-in-one-day" books that have 0 roman letters, and expect you to know 4 kyuu kanji + kana right from the beginning. My advice is to get Ultimate Japanese Beginner-Intermediate (ECS's suggestion, for which im still grateful). That book is THE THING. Next get yourself a dictionary, possibly something of Oxford origins. A Kanji dictionary for future days. A grammar book. Once you have all these you can start randomly buying anything thats Japanese language related. While they all arrive do Japanese is Possible (JimmySeal). Yeah, something like this. Feel free to disagree with me.