My biggest regret is probably not seriously working on reading earlier (I didn’t seriously start until level 20), but it is hard at first. And finding level appropriate reading material can be really difficult when you are in that very beginner stage. For that, I would really recommend using https://learnnatively.com/ to at least try to broadly gauge the difficulty of what you are looking at reading.
A lot of good stuff shared here already that I’ve seen people have success with, but if you are looking for free things, you can also try making an account on https://bookwalker.jp and following the The BookWalker Freebies Thread. You can get a lot of free or extremely cheap volumes (mostly manga), some are only free for a time window, but some you get to keep forever!
Most series also have between a 30 and 50 page free preview, which when you are first starting out can be a ton of reading material, if you don’t mind chapters getting cut off sometimes and skipping around between multiple series a bunch.