We must know the principle of art first, and the foundation should be improved by hand drawing. Understand the sketch relationship such as black, white and gray boundary, and draw it easily. The color of painting mainly depends on the sense of color, but it is still based on the black-and-white relationship of sketch. It is suggested to buy some elementary sketch principle textbooks, which can draw squares well and is not a problem for others. Everything has structure. Come on, hehe ~