1) have a background face
2) double the layer and desature it and put it in hard light to accentuate the contrast
3) create a layer with one appropriate texture ex:
http://lh5.ggpht.com/_fN_Lam-iHcc/R0lINU7CKLI/AAAAAAAAA6Y/2cNimV8JlRQ/IMG_0052.jpgAjust it in size and move it if necessary to have a nice placement on the face, take care at the light source provenance for more realism.
( you can displace this layer with a blured copy of the desatured one to give some volume to the texture in case you hare using a geometric texture )
4) Make a layer mask in full black and paint in white with a soft brush the skin part, where you want to reveal the texture. letting the eyes and mouse intact
5) Double the texture layer, put the first one in soft light and se second in overlay at 25 % opacity
6) with a copy of the face layer decompose and find the more contrasted result in the RGB, threshold it to have a marked shadow, a gautian blur at 8 will soft it a bit, and finaly put this layer on top of the stack in multiply mode at 25 % ( you can add to it the same layer mask of the texture layer, so the accentued shadow impact only the skin part )
7) play a lot with the layer opacity to fin the right balance
Cook it with salt en peppers
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