Just took my first JLPT (N3) and honestly the biggest lesson was: it’s all about practice patterns. Classes give you the foundation, but the real gains come from grinding exercise books — the problem is they’re like 2,000 yen a pop 
So I built a free website with practice exercises covering grammar, vocab, and kanji for N1–N5. You don’t even have to register email or even do anything, just visit to practice LOL. I’m using it myself to prep for N2 now.
Sharing in case it helps anyone with the upcoming test!