From the outside to the inside, from the whole to the part

For example, a triangular plaster and a spherical plaster are located close to each other on a piece of cloth. After the shape is accurate, start with the dark side to determine the dividing line between light and dark. Focus on characterization

If the line is too thick, it means that your pen is not sharpened well, your technique is not skillful, and you look at the object too locally. You need to make a general approach. These reasons can be solved after you practice for a long time.

It will be great if you can master the overall picture after practicing for a long time. You don’t have to worry about whether the thick line is a straight line or a curve. These are all problems of graphical depiction. Some people also like to use curved smear balls. I suggest you copy the human body sketches of ancient Western masters. This is helpful for sketching and color toning. Don't be academic