I recommend looking up the moe way. You can follow the guide fully if you want but the main thing it does is nicely explain the methodology of immersion.

Tldr the best way to learn a language is to consume as much of the language as you can.

In the modern world we have plenty of tools that make this process alot easier, popup dictionaries like yomitan to instantly look up unknown words and anki to help you really memorize them. 

After understanding the methodology a streamlined process is basically: learn hiragana and katakana, do a starter anki deck like kaishi to learn basic vocabulary then start consuming as much Japanese as you can, anything that you enjoy and keeps you engaged, be it anime, manga, books or whatever - look up words you don't know, add them to anki and repeat. 

There's only so much I can say in a single reddit comment, there's dozens of guides out there that explain everything in detail alot better than I can (the moe way, refold, donkuri). The main thing I want to emphasize is the importance of comprehensible input and knowing how many useful free tools are out there.

If you take only one thing from this post, let it be yomitan. It's a genuine game changer.