Scan your painting (or open peeling.jpg from the projects file, which can be downloaded here) and select Image > Adjustments > Desaturate (Cmd/ Ctrl+Shift+U). Go to Image > Invert (Cmd/ Ctrl+I), select Image > Adjustments > Levels (Cmd/Ctrl+L) and increase the contrast, changing the input values to 40, 1 and 244. Select the best parts and place this new layer over the background. Set the blending mode to Screen and the opacity to 44 per cent.
To create the aged paper texture, get a thick paintbrush, a white sheet and a cup of very strong coffee. Start painting the sheet with coffee and as soon as it’s dry, scan and import it to your illustration. Alternatively you can open coffee_texture.jpg. Put this layer on top of the others.
Open dirty_burn.jpg (I created this texture using the same technique described in Step 07) and copy into a new Alpha channel in your illustration. Go to Image > Invert (Cmd/Ctrl+I), then Image > Adjustments > Levels (Cmd/Ctrl+L) and change the input values to 15, 1 and 245. Generate a selection from this Alpha channel, and create a new layer above the old paper texture layer. Fill this selection with a dark grey tone (C=0, M=0, Y=0, K=80) and set the blending mode to Color Burn.