Hey! I think you made some great progress. I really like those environments.
My advice would be to do a lot of drawing in general. Maybe you already do something similar, but for me it really helpes to do 1-2 sketchbook pages consistently each day. Value studys might be a good idea too, they help to organize paintings better.
And as for books, I would recommend Painting with Light and Color by James Gurney. Sorry if that was already recommended!
@tinDeer Thanks I already have the Color and Light book. Thanks for the tips.
I am just here to tell you that even if i can't stand this type of artwork you doing(furry).
I will say don't let people like me stop you for doing what you like.Art is like taste everyone got there own.