In this  sketch tutorial you can work in a simple and easy way the shadows.
I used only paynes gray as a base for shadows.
A great training simple beginners of light direction.
Line and wash in my style.
This is a tutorial that is on my channel on youtube:https://www.youtube.com/watch?v=msH6al2o2u4&t=44s

6x8 inches
sketchbook paper 300g hot press 140lb canson Heritage
and Watercolor winsor e newton
:)