this guy is good
it's a method. it's studying by watching, reading, listening to content in the language you want to learn and especially for JP, supplementing it with flashcards like anki. so this could be anime (w/o english subtitles), youtube, manga, novels, visual novels, video games, dramas and even western content with a JP dub
I don't think I personally used this guide but I know a lot of people reference it so you could check it out if you'd like to learn more: https://donkuri.github.io/learn-japanese/guide/