Figure textures from photos need a lot of "touch-up" but it can be very rewarding. It is best if you can photograph the model yourself using fairly even frontal lighting with a little fill on the sides - and be sure to use a normal to slight telephoto lens at about navel level to minimize distortion. Also get close-ups in the same lighting of skin textures, hands etc to be worked in later. Once you have you photos and pieces in a paint program, You can use a deform tool to stretch the skin to roughly fit the map which should be on a separate layer for reference. Remember that there is progressively more stretching as you approach the sides. I usually do the "stretch" in 3 or more steps so it doesn't look too distorted in any given area. Of course air-brushing and smudging are also necessary. Working with existing photos of people can be frustrating because you rarely find a neutral pose that is evenly illumiated, but by using bits and pieces from photos , and creating a skin-like wash you can get some nice results. Both techniques need final blending at the seams - a clone tool helps match the various pieces at their joins. good luck - its a lot of work, but a lot of fun too.