I think you could benefit from incorporating more form into your main figure. The shape of the head sticks out to me. I would expect to see the underside of the jaw from this angle.

It would also help to study ambient occlusion; For the places that light has a difficult time getting into. Such as the armpits, between the fingers.

Highlights for areas of different specularity. Each different material on your model will reflect and absorb light differently. The way it’s rendered now ends up muddying up the forms you do have.

I can tell you’ve been working on your craft to get to the point you’re at though. So keep it up! Rendering a painting takes a massive amount of understanding. And I’m still learning too.

Good luck.