Good question, I would say Manes by Mell on youtube is pretty informative. Aside from that welshiecurlgirl on Instagram has a lot of posts about caring for curly hair, a lot of it is towards people with fine and/or low density hair. I recently found science-yhairblog.blogspot.com from welshiecurlgirl and it’s more technical and talks about studies of hair. I’ll have to gather some more resources and then pin it on this community. I’m always up for finding new sources of info.