I made 3 lighting variations 
Timelapse
The side of the image that I have the hardest time drawing is the obstructed/covered part, and in the end I like to simplify it. Criticism and suggestions are always welcome, and for that I am very grateful.
What do you mean, with obstructed/covered parts? The background? 
Also for the “luminous book” one, it feels like some shadows are missing, especially on the face.
I like the night one 
It’s eye-catching to me. Maybe it’s the contrast between the face and the hair?
I mean like the curves of the body, the upper arm to the right shoulder, which when sketching I have to really pay attention to even though it will be covered by loose clothes or other parts of the body.
You are right, for that part I am still learning to guess where to place the light and where to place the shadows. 
I found that one on pinterest. Maybe it could be helpful to you?
Also, for the obstructed part, maybe try sketching the body separately from the things covering, in this case, the clothes and the head.
I pinned it right away, thank you 
