How to draw a sense of block with gouache

When you say quick face, do you mean three-dimensional sense? If so, let's assume which direction the light comes from. Generally speaking, the color of the irradiated side can be lightened, and the non-irradiated side needs to be darkened. Everything in life is three-dimensional because of the existence of light. Generally, don't add too much water to the cloth, because the cloth will absorb water and spread. I hope it helps you.