I think the most important thing is to find something that you engage with on a personal level.
In terms of learning grammar, I went through the Genki 1 textbook way back when and hated it, simply because I found the tone/example sentences to be so incredibly boring. Then I tried Bunpro for a while, and it was a bit better, but still quite dry, so I ended up not sticking with it. This past year, I’ve been using Marumori (see the linked thread below for details) and I’ve been enjoying it a lot more, simply because the tone of the lessons is more entertaining. It does also have additional vocab to study beyond what Wanikani offers.
I’ll echo the other recommendations - book clubs, looking at the reading resources trunklayer posted, studying vocab outside of Wanikani, etc. Whatever you choose, though, my recommendation is that it ought to be something you find genuinely interesting or fun. For example, if you’re like me, and find your eyes glazing over reading news articles in your native language, trying to
by trying to read something like NHK News Easy is going to be intolerably dull, and (probably) impossible to stick to long enough to actually do the absorbing. Whereas choosing something you find interesting, even if it’s technically quite a ways beyond your current level, might give you additional motivation to stick with it longer. Finding something that’s both at the right level AND interesting would be ideal, of course. 
Ironically, I think one of the things I’ve found most helpful for me for getting used to reading has actually been listening to as much Japanese as possible, and then doing my reading out loud. I’ve been watching anime and dramas, with and without subtitles, and listening to music in Japanese for years - I’ll regularly now read something silently and feel totally lost…then read it out loud and realize that I’ve heard such and such character using that word, or that that grammar point is in a particular song lyric. I might not know yet exactly what it means, but if I look it up at that point, having that association makes it stick in my memory better.
I have no idea if that specific idea would be helpful for you, but making the connection between something dry (grammar/vocab study) and something you’re interested in seems to me to be the key to making progress. Best of luck with your studies!