if colouring in photoshop you could blog the face in with some colour. paint roughly all over the face (new layer of course) and then hide this layer, go back to the original later and select the white of the face using the magic wand tool, then CMD + Shift + i (windows: CTRL + Shift + i) to invert the selection, then back on the colour layer and hit delete.

This should give you a colored face, you can then use the dodge and burn tool to add shading, dodge to lighten and burn to darken.


Also, to make the horns more - horn like in there appearence, you can always simply rotate them, so that the baseline is horisontally adjasent to the text
Here is what I would do: http://grab.by/5jET

Hope this helps.