Mini Painters, what's been the steepest learning curve for you so far?

Mine has been unlearning everything from art school and my professional career in commissions. I always work lightest to darkest there, but here I've been learning you go from darkest up to the lightest; that's been really difficult for me.

Also not using a lot of paint on my brush. I do big paintings usually, so barely getting any of my tiny brush is difficult still.