>>277646
Expert Japanese learner(he/him) here.
Learn hiragana and katakana first. Should take you 3 days at the least and a week at most, try and look for a site that shows you a kana and asks you to write the English of it (た = ta etc) or vice versa(ta = た) whichever is fine, then just grind that until you remember them. It'll take a few months until you really get used to them, just bear with it and look the kana up whenever you forget them.
Get Yomichan or one of the thousand other Japanese pop-up dictionaries, they're absolutely necessary. Get Anki as well, I recommend Core 2k/6k(optionally 2k/6k/10k) as well as VN Core 1250. VN Core has some important words in it that don't appear in the other deck, so you'd probably be best off going through the two at the same time with 10 new cards each. Base is 20 new cards per deck, which I think is just right if you're doing a single deck at a time. When you've gotten a decent grasp of the language(3k cards known) then you can try upping to somewhere between 20-50 new cards a day depending on how good you're handling things.
For grammar, Tae Kim's is not bad. It doesn't go in too deep but that's fine. If you're not autistic enough to enjoy reading that sort of stuff then just go through particles and then read the other parts of it as you happen upon those grammatical points in actual Japanese content.
You don't need to learn to write kanji nor their stroke orders. You should give it a try since I've heard many people say it helps them remember the kanji, but I personally have not done so and remembered them just fine. Note that not writing any kanji at all will cause you to be completely incapable of writing them with your hand(you can still read and write digitally just fine) so you'll have to do something about that eventually if you want that skill. You'll just be writing a bunch of kanji until you get used to it though, so it's not that big of a deal. Do not bother with learning kanji in isolation early on, do that after you've gotten to N2 at the least(unless you're doing it as a side activity to pass the time). You can grasp the meanings and readings of many kanji by just learning the many two kanji words present in the language, and after 3000 or so words this'll start giving you a significant boost in your learning as you can partially or in whole guess the meanings and/or readings of many words.
You don't necessarily need to learn grammar by going through a book or a grammar guide, but I as someone who has never touched anything other than the particles section of Tae Kim's guide strongly advise that you do so. It's far faster than trying to naturally comprehend the grammar, although it lacks the joy of cracking at the same patterns over and over again until you suddenly just "get" it. You can try to do so, but there's really nothing you gain from relying exclusively on instinct to grasp grammar.
You should try to engage with Japanese content right after learning kana, ideally something you enjoy. Many people go through Yotsubato and I have done the same as well, but really any manga that has furigana for all words is fine. Even with basic stuff like Yotsubato you'll be getting fucked over nonstop at the start but there's nothing you can do but keep reading until you get it. Anime with Japanese subs, VNs with textractor and other software(or alternatively ones that allow you to switch between Jap and English instantly for example Steam version of Little Busters or Yuzu VNs) are also good. There's a lot of software that can help you consume content so I recommend you go around the many /djt/s asking what people use. I can't be assed to write about them but there are also many other resources such as sites that contain Jap subs for many anime etc which you definitely should be aware of. Niconico may be small now but it still has much interesting stuff being posted in it daily and you should definitely take a look, even if not now but later on in the future. I use it everyday. If you're going to do so then I recommend that you make an account, turn the "block sensitive contents" setting off, and use a Jap proxy while going through it. You'll be able to access blocked videos and make comments on the Japanese side of the comments section. You can make comments without a Jap proxy if you have a premium account, but (while untested) a Jap IP is probably necessary to see blocked videos.
I passed N1 after a year and a half of studying, and that was while working 10 hours a day and spending 3~ hours on transport, you can definitely do the same. You will obviously need to be quite diligent to manage that though. [spoiler]Nevermind the fact that I missed one out of every two days of my Anki[/spoiler] It's been almost 4 years since I first started studying and I can now safely say that I am Japanese in all ways but physical. I stopped studying after getting the N1 and have been casually coasting on since then, absorbing the few knowledge I lack from the various content I enjoy.
If you ever start hallucinating kanji while awake, having dreams where you're made fun of by Japanese women for not knowing enough Japanese to reply to their questions instantly, or have terrible headaches that can last anywhere from 2-10 hours dependant on how much content you've consumed in Japanese that day, just know that these are all natural and temporary side effects of having your mind raped by the language. Keep calm and carry on learning.