The artist of this piece used creativity when shading by using stripes. I think the three areas of emphasis are the "s", the area around the sunglasses and ruler, and the saw.
This is a drawing from Durer's piece Melencolia. I'm going to make everything a little darker, but I will pay more attention to the wood piece and the circle to help them stand out. I will also try to make the lines a little cleaner.