Mostly just was looking for actual culturally relevant conversations in every day, natural Japanese because it became super apparent early on that DuoLingo was only teaching the most formal way of speaking. A lot of just random kind of family home videos people uploaded and news from Japanese media outlets.
Outside of that, I have a flash card program on my PC but I can't remember the name off the top of my head (and am not home to look). That helps a lot with learning more vocab.