Understanding the anatomy of human hands makes it way more easy to draw them.
I am always starting with a rectangle as the basis (pic 1) and adding the different parts of the fingers as thin ellipses (pic 2).
Interesting use of color to frame the hammer.
Use of tone to communicate the surfaces of the drill handle.
Nice use of white pencil to add highlights but I think the dark outline blends too much into the cast shadow and background.
Quick motion study with simple lines and shapes.
I like how the color was added quickly and evenly over the whole watch and then the form was delineated with shadows and highlights.