In this video:
I used Maya to generate separate Ambient Occlusion maps for the individual head meshes. This gave me specific control over how each map was used in composting over a flat, base texture in Photoshop.
Once the A-O and base colors were composited together, I saved a PSD and brought the organized, UV mesh in to bodypaint with the PSD. I proceeded to paint a layer of stubble, blush, and simple pseudo-lighting in to the skin. When finished, I exported the PSD and applied it as a texture in Maya.
You don't have to use bodypaint, but I like its brush selection, and ability to utilize layers and layer modes like photoshop.
Tools used in this video: