I did this kinda quickly sorry but you need to keep in mind where the light comes from. I used the shadow you out for Kenma's neck to figure that the light should be up to bottom and right to left. Then use your imagination to see the things you are drawing in 3D and figure out where the shadows would be. Generally the closer the shadow the sharper it is and the further aways the more it becomes blurry. Parts of the shadows are darker than others so don't hesitate to make it dark. I could keep on but in general use refs if you aren't sure or look up tutorials, shadows are a tricky thing | Artwod Feedback