Sharmendra D. answered 03/25/19
21st century Digital Bob Ross
I think one of the best methods is practicing from real life. So setting up an object next to a good source of lighting, (window, lamp, etc), and really examining the object/environment, how the light is bouncing off the object, and the shadow reflections. This way, you will be able to see how each individual object with various surface textures will be affected by light.
If you have a portable lamp/light source, trying moving it around the object and seeing how it's manipulative the shadow (I used to do this in college).
Great video sources: https://www.youtube.com/watch?v=V3WmrWUEIJo
https://www.youtube.com/watch?v=HdqKc7klwE0
let me know if you have any questions!