Excuse me, how does gouache figure adjust the color of nose, eyes, mouth and face?

Everyone's facial color is different. Generally, the following colors (khaki, scarlet, crimson, olive green, ochre, white, etc.) are used according to the vehicle type and the surrounding environment. Men's cheeks tend to be cool because of their beards, especially near their mouths and jaws (which can be turned into olive green and ultramarine). As long as you pay attention to the contrast of different red colors, the upper lip is generally cold, such as strong reflection.

The above is knowledge and experience. If you really want to draw good colors, you should observe carefully, sketch more and train your ability to capture colors. I hope it helps you.