What I've been doing recently with some students is making videos of some topics which they don't get and it seems to be pretty effective in the sense that I don't have to keep explaining concepts as whenever they need a refresh the video can generally help.
I do have a youtube channel for it, though haven't really put anything too complex up (just really basic stuff). If there are enough people who need help with a certain area of any subject listed in my signature (or if you're from another state just tell me which topic), I'm happy to make a video on it as well. They won't be on how to answer extremely difficult questions (though if I see a recurring question that comes up, I'll put it up), but moreso to build foundation on things that you might have missed/not paid attention to at school.
Just let me know on PM/here

If anyone else is keen on helping out like this it's also appreciated. If it takes off we might even chuck the videos in the notes section.
Just keep in mind that a lot of topics are covered by other places on the net, so do a quick search before asking maybe