Hmm, the shading here looks really nice. You are spot on. Maybe add a bit more shadows to the skin? The brightness of the skin does help the viewers eyes pull towards Frisk's face. However Frisk is in a lighted cave. Maybe add a bit of shading under the hair?
I'd imagine a bit more blue lighting as well with the white. Since the mushrooms are blue of course. But if you were avoiding the saturation of blue to prevent Frisk from blending into the background its fine.
Also Frisk's clothes could use more shadows too. Particularlly under the arms.
Overall it's well done. Try to remember clothes and hair can have shadows too, not only your light source(in this case the mushrooms). You have a good grasp on visual lighting. I can't really say too many suggestions. Good job on this work! It's really nice!

awww adotable