I would learn hiragana and katakana first . Also vocabulary words. With out vocab words you wont know what people are saying so its one of the most important things. Hiragana, katakana, and kanji look really different from each other so its easy to tell them apart.
Example:
Watashi
( I)
わたし ( hiragana)
私 ( kanji)
ﾜﾀｼ (katakana)