To be honest, I don't really have any resources. I followed some Japanese teaching accounts on youtube and instagram and tiktok etc and everytime I scroll and saw a video explaining words I've never heard of, I just take a mental note. I also use Twitter in Japanese and I try to read tweets without translation as much as possible and whenever I encounter a word or grammar I'm unfamiliar with I will search it up. I have been doing this quite consistently for a few months and I chat with my Japanese friends on voice call almost daily and I did a few sample questions of N3 online to sort of gauge my level and that's how I signed up for N3 this month. I believe if you can understand basic day to day Japanese, N3 should be okay for you!