I'm took Japanese for three years at University level.
The most important thing is learning the hiragana katakana.
Then, get a book on kanji. Kanji is based in grade levels, and books will have them listed by grade, so you can read first grade, then second grade, etc.
But don't get the wrong idea. The grammar is completely different from English. It's a difficult language. You can't just read it and understand, as meanings vary wildly just from one particle being changed to another.
For example:
1Nani ka nomimasuka: Are you/will you drink something?
2Nani o nomimasuka: What are you drinking?
3Nani ka nomimasenka: Won't you have a drink something (implied: With me?)?
Literal:
Nani: what
ka: choice/some kind of - when paired with nani can read as something
o: direct object
Nomimasu: drink
ending ka: question mark
masen: negative form
So the first is:
1 something will drink/drinking?
2 what drinking?
3 something not drinking?
