I used a set of (paper) flash cards, a book, and two posters that came with the cards.
With them, each kana character has a picture associated with it, for instance く, which is a picture of a bird with its beak making the "く" sound. It made it very simple to memorize hiragana and katakana, because if you stumble on one of them you can quickly call up the associated image in your mind, and there it is. Associating the sounds with images or scenarios allowed me to begin not thinking of them in Romaji but rather as their own particular sound/character, and for me at least that helped immensely.