Well like I said in my post, I don’t think I ever could have done it this efficiently on my own. My skills right now are the result of 3.5-hour uni classes and then 2 or more hours of studying/homework every day for the past 10 weeks. But I can try to give you some tips!
We’ve been using the Genki series of textbooks (1st year textbook and workbook) and I think it’s pretty nice. The chapters spell things out very clearly and introduce just the right amount of new concepts every chapter. We also use the workbook, mostly for listening practice. The workbook comes with a CD with conversation tracks that correspond to the workbook assignments, basic language class stuff basically.
All the Genki materials are very easily found online for free, PDFs and mp3’s from the CDs.
What works best for my memorization is handwriting whatever I can. I filled in, like, four hiragana tables daily in the days preceding the class because we were expected to learn all of them within two days. Same with katakana. Just repeat, repeat, repeat until muscle memory kicks in. Same thing for kanji. We learn about 15 -30 kanji per week and I’ve found that to be a little excessive. Try 10 per week maybe. And USE them. If I don’t write a kanji in my assignments repeatedly, I lose it so quickly.
Speaking Japanese out loud is one of your greatest assets, and the best way to learn to correct yourself. You have enough experience with hearing native Japanese speech that you probably have a good sense of when something comes out of your mouth and doesn’t sound right. You’ll build on that as you learn more and more grammar. When I take tests, I end up muttering to myself a lot because hearing my voice gives me a completely different perspective than just reading my answer on paper.
And of course, there’s the fun part of trying to talk to Japanese speakers whenever you can, native or otherwise, through text or speech. That forces you to learn new vocab to express the things you want to say, rather than adhering to some assignment’s guidelines. A woman I spoke to also recommended keeping a journal in Japanese. Nothing fancy – just write what you did that day. Very simple sentences, but you’ll probably look up at least 1-2 words every day to describe what you did. Then boom, you have two new vocabs and contexts to remember them by.
I don’t know if any of that will help or not. I’m not sure that there is really an “efficient” way to learn JP outside of an intensive course like this one, which probably isn’t offered by a lot of universities. It’s p hard and my JP isn’t the greatest by any means but it is lots of fun even though I am suffering ヾ(*´∀`*)ノ
EDIT: Forgot to mention quizlets!! Quizlet is a gr8 website for cramming vocab. It quizzes you and makes you go over the words you get wrong until you get 100%. You can put whatever words you want in there. That thing is my lifeblood and my #1 study tool, I just cram all the shit into my head at once. I just did it tonight and learned like 40 new words in half an hour. Ofc you can take your time with it, I know cramming doesn't work for everyone quite as well as it does for me, haha