Pucker up for a sloppy and cringy wall of text.

Duolingo is trash for learning Japanese. Delete it and never look back.

I've studied for two years on my own using various methods and everyone tells a different story, so I'll talk about what I do now. The list of programs I use are:

-Anki: A Spaced Repetition Software (Flashcards) and one of the pillars of my studies. Not the most user friendly, but highly moddable. I use this guy every day, I recommend taking a look at Matt vs. Japan's videos on anki and his MIA.

-Yomichan: A browser extension that parses text on hover. It shows you information about words by looking them up in previously imported dictionaries. It has integration with Anki, so you can add word cards automatically as you run into them. There are some good "free" dictionaries around, but I don't have a compilation.

-ShareX: Program to take screengrabs and audio clippings.

-Language Learning with Netflixt / Animebook: LLN is a browser extension for Netflix. It basically makes the subtitles pop out so you can select them. It also grabs every line and puts them all in a sidebar, so you can click on each one and jump to that part of the movie/show. Animebook works in a similar way, but you have to impórt your own files, both the video and subtitle file. I use Yomichan to look up the words, the integrated dictionary is garbage. Here is a demo and in-depth manual and here is another manual for making cards (Matt copied this guy, btw).

-Textractor: A program that hooks into Visual Novels and extracts text. I use this one mainly for Eroge (Rance-chads rise up!), but you can use it for normal VNs too, like Steins;Gate or w/e. I use the MIA dictionary or Yomichan to look up the words, then I make 1T Sentence (Sentences which have only one unkown word) cards.

-Capture2Text: OCR program that I use for manga. I look up the words on the MIA dictionary or Yomichan.

-IMABI: Reference website. I don't use this much, but it's great as reference material.

-NHK NEWS EASY: Short news articles in Japanese. With Yomichan you can blast through these articles, which are great immersion material.

Other things I have personally used:

-Paper flashcards: Ever since I discovered Anki these have been collecting dust. There is no point in using them when SRS exist.

-Genki: Textbooks meant for a classroom setting, but totally fine for people learning by themselves. I think these are good, because they provide a framework for learning grammar and vocabulary in the beginning stages. There could be better material out there. I got the pdf of Genki I, and the audio files. I can PM you if interested.

-RTK/Heisig: This is imo the best thing ever for learning Kanji, hands down. It's a method for learning, recognizing and retaining the writings and meanings of Kanji. When combined with the premade Anki deck and the RRTK, you'll nail kanji down in no time (Read: A couple of months to a year). I hear there are pirated copies of the latest version around, but the older ones are easy to find.

-A brush pen: I bought this for writing Kanji. I still use it sometimes, but I used it mainly for the RTK binder I have. Even if you don't plan on using handwriting, I think it's a good idea to get the feel of each stroke.

-Squared/Grid paper: I used this at first to take notes and to write on, instead of sullying my Genki books, I use it now to practice handwriting and to get the feeling of some words. Combine this with a binder for RTK, imo.

Other resources I've seen, but not used personally:

-WaniKani: I tried to use it, but my smartphone is too shit and can't run it.

-Minna no Nihongo: I hear that this book is not so good, but have not taken a look at it.

-LingoDeer: Never tried it, but some people say its a better duolingo, whatever that means.

Things to keep in mind:

-Pronunciation: The first thing you should know is how to correctly pronounce every single sound. Start on the right path and it'll be easier than removing a bad habit. Don't be this guy

-Pitch accent: One of the most underrated things. Rarely gets mentioned within normie circles. Watch a couple of videos about it, so you can recognize it. After a while you can watch Dogen's series on pitch accent.

-Culture: It's very important to keep culture in mind, as it is intertwined with the language. Things like levels of politeness, yakuwarigo, unique onomatopoeia and other unique terms are key to fully understanding the language.

-Motivation: It's probably the most important thing. Set yourself goals. Return to previously seen material, Look up to doing something. With no motivation you'll go nowhere.

-Results: Japanese is a hard language for people who only speak English. It might take a long time to be able to watch anime without subs or to read without a dictionary, but I can tell you this: I can see the results with every word/sentence I understand. Re watching old series with japanese subtitles, or with no subtitles at all, feels a lot more satisfying now. The same goes for the times I replay some H-scenes from previously played games ( ͡° ͜ʖ ͡°).

I took some of these ideas from Matt vs. Japan and this document. I am by no means qualified to teach Japanese, but I hope this post helps you acquire some powerful tools for learning.