I don't know if you have sharp eyes to discover the characteristics of models as soon as possible. If you can, I suggest that you practice some copying instead of sketching. Pay attention to the line when copying, and try to succeed once. Because the most original findings are often more open than after training. It is easy to be bound by the normal proportion after training! If you think there is nothing too personal about people, that is, painting people like them, then you should consider finding a training. But training him is not very good at relying on comics, only to improve your skills, or to help you understand other people's institutions, or to find space. But in this case, you can understand it by reading the basic book!

If you copy, don't copy all people, but deliberately copy local facial features, such as drawing this eye or that mouth. You can assemble people by yourself if you draw too many pictures. After that, you can make some changes according to your preferences, and finally you can draw your favorite image! The method is the same.