So I recently got into WaniKani and as far as I’ve experienced, it is extremely good at teaching Kanji / Vocab. I do understand why I have to wait and I can also see the merit of doing so by looking at my progress.
I’d like to spend more time learning Japanese, but don’t know what to do.
I don’t have any Japanese knowledge apart from WaniKani and watching anime (rough meanings of some common vocabulary / sentences).
Do you have any suggestions on what I could do?
I’ve considered reading simple books, but I’m unsure of whether I’d actually understand anything / learn anything from it.
You can start learning grammar as soon as you want. That’s just their recommendation not some ironclad truth. If you like videos there’s ones like Japanese Ammo with Misa, or you can use references like Imabi, Maggie Sensei, etc. Or if you prefer a textbook you can always pick up something like Genki or Minna no Nihongo. There’s a whole lot of choices on the spectrum from the free to the paid.
I strongly recommend you start learning grammar and ignore Tofugu’s suggestion. Good grammar textbooks (instead of random sites) will teach you any kanji/words that are used in each chapter. So it’s not like you need to learn the material through WaniKani first.
You won’t get anything out of reading books until you have at least a basic understanding of grammar.
I used Japanese From Zero. Many people use Genki, and there are other textbooks as well. My main suggestion is get something that includes exercises and make sure to do them. Practice is really important for fundamental grammar.
Besides the textbooks etc. already mentioned, have a look at BunPro. It’s an SRS app like WK, but for grammar points. A lot of people around here seem to use it, so you can find plenty of experience reports by putting the app name in the forum search. I have only been using it for about a month, but I find it very helpful. The only problem I have with it is that I’m not as consistent in doing my reviews over there as I am with WK.