A great easy to follow tutorial. First use the liquify filter ( filter > liquify) to stretch areas on the face, particularly arching the eye brows. A good tip is to try to make the face unsymetrical. After adding a layer of texture and aligning it with the photograph below, choose hard light from the layers panel drop down menu with the texture layer selected. Erase the unwanted areas and use the dodge and burn tools to highlight specific areas. A good tutorial for changing the eye colour can be found here: Zombie eye.