The lighting looks flat because you can't decide on where the light comes from. Parts of her are shaded as if there was diffused ambient light around (chest), but also weak light from above (horns, face), green light from behind her(arms) and green light coming from the glowing face. She is standing in some sort of grey smoke that reflects some of light back but none of it lands on her body. Looking at her arm/hand position it seems she is holding the glowing face somewhat in front of her. I limited the light to it and added a bit of rim light from behind to make her look more 3d and fit better into environment. Try to practice shading basic forms (cylinders, spheres, boxes) in various light settings - it will help you to get a better feeling of it. Good luck and gave fun! | Artwod Feedback