With screentone, you can apply screentone easily, a commonly used tool in creating mangas.
First, prepare a line drawing.
Open ① the Layer window, Add ②a new layer, Drag ③the current layerunderneath the line drawing.
Select ①a blend mode. Tap on ②Screen Tone.
This time, for shadow on the skin, after selecting ① Dot L8 screentone, I set ② opacity to 15%.
Using the Brush tool or the Flood Fill tool, you can easily apply screentone.