|Color and Light||1.1||Do Assignment|
|Color and Light||1.2||Do Assignment||1.3 | 1.4|
|Illusion of Space and Atmosphere||1||Do Assignment|
|Personal Art||1.1||Do Assignment|
Find or make a drybrush texture.
Paste it over the image. Use layer blending modes to apply it to the image.
Alternatively, make it into a brush or multiple brushes and use it to distress the drawing you're trying to edit.
Try ArtRage. The brush effects are amazing.