Hey Nio, I see the form in the arm coming along well. One thing I will say is be careful when applying the dark shadows. In the edge of the torso approaching the armpit seems to be a faint rim light contrasting against the inside of her arm, so I would try erasing some of that area to lighten it up some more. Also, if you are using charcoal, I like to use a paintbrush with my shading so I can get some smooth transitions in the shading, and then going in with an eraser and white chalk to introduce more highlights. But I like how you are not afraid to go in with dark shadows.