I passed N5 in December. I’m not sure how far you are into your studies, but with the test only 3 months or so away I’d recommend focussing on resources other than Wanikani for now. While it’s great for learning kanji, it won’t teach you the vocabulary necessary for the test, and can be a bit slow and time-consuming (you need to complete level 10 to have seen 95% of the kanji for N5). I took a break for a few weeks before the test because I needed to focus on cramming grammar and filling out my vocab.
My favourite resource was memrise, as it’s well designed and uses SRS in a similar way to Wanikani (it’s also free!). I learned most of the grammar points for the test from there, although I had a solid grounding in the basics already.
Anki is also a popular SRS system, although I personally don’t like it. I think it may have more comprehensive grammar decks than memrise though, so it might be worth looking at.
As Leebo said, past papers are the best way of passing tests (once you’ve learnt the material). Often questions are designed in ways that you don’t expect, but are generally similar year-to-year. By doing previous questions you’ll be able to see patterns of question types, and understand what the examiners are looking for.