It's fine to abandon the tablet for a while. Despite what I said about autism, I still think pencil and paper is the sword and board of drawing.
Even with a display tablet, I find there's this weird loss of feedback and context, and zooming in becomes a necessity rather than an option. And things start to look wonky when you lean into the paper.
Okay, maybe Fun with a Pencil would be a good book. I don't know about chibis specficially, but the thing with these simple characters is to learn to place really basic 3d shapes in space.
Also look at the Made in Abyss manga. It's more loli/shota than chibi, but the highly simplified characters seem to pop out of the page.