Not the original poster but current student of Japanese here. Number one thing to note for learning Japanese is motivation. Although anime is awesome do you feel it is strong enough to keep you motivated to study every day?
The drop out rate of language learners is huge, learning a language is all about keeping yourself studying, even if it’s only in small bits.
Ramble over, now onto my tips!
First, before anything else, you’ll need to learn the Japanese kana. These are two alphabets. Sounds bad right? Nah, they both have exactly the same sounds, but one (hiragana) is for Japanese words and names and the other (katakana) is for foreign words and names.
I suggest using tofugu’s hiragana and katakana guide
After you have both of those locked down, you’re ready for a Japanese textbook. My uni class used Japanese for busy people (kana edition, NOT romanji) , but I personally suggest genki because it introduces you to the third alphabet, kanji. Those are the chinese characters. If you use jfbp then you should look up the kanji for all the words you come across in it.
Secondly, you will need a revision method! I use anki app. Which is a free srs flash card computer program and paid phone app. They both link together so you can do flash cards on the go. You basically use it to make your own flash cards. You can import pre made card decks from all popular Japanese textbooks but I find it’s easier to learn if you make them yourself.
Now for kanji. Kanji can be quite daunting, especially the more complicated ones. There are several methods people use to help. One is “remembering the kanji”. Which is essentially a method of looking at a kanji and turning it into something memorable. So person 人 sort of looks like two legs, so a person walking.
My method is breaking down the kanji into its components and making a memonic out of it. So mathematics (study of) is 数学, which is made up of 米女攵 and 学.
Other methods include apps like scritter or WaniKani (srs learning system. Scritter lets you write them too but I don’t like it.).
Whatever the method, learn in small, related groups. So like 10 animals a day or 12 furniture items a day.
Seriously though, my top tip is to just keep going. Even if you feel you can’t. Just keep learning. If you don’t want to do anymore kanji for a day, go over some grammar or words you already know. It’s all about retaining what you’ve learnt.
Extra stuff: practise saying the sounds to yourself. Especially the r sounds. Look up a YouTube video on them. It’s quite hard to get right on the first go for a British person.
When watching anime, try and listen for words you already know. Watch anime and films too!
There’s a really good website called the Japanese foundation. It has tons of gcse Japanese resources on there and they list events. They did a Japanese film week in my town a few weeks ago
That’s all I have to say. Maybe find someone interested in learning with you. Having someone to compete with always keeps me motivated to learn more, but that’s just me X3 pm me if you need any more help.