Hmmm what do u want to know? i'm no expert, but i can tell you how i do it. I use paintshop pro 7. First u need photos of bodyparts and face and u need skin seamguide/templet for the figure you are going to make a skin for.
I mostly do high delails in the face, hands.... Legs/arms/genital i don't do very detailed, but the same technic would of corse apply to those parts too.
I start with the photo of the face.
I erase the eyes.
The skin on the outskirts of the face usually have the same /or close color and lighting so i decided what part of it matches the color and lighting of the face the most.
I make a seamless tile of a small part of that ouskirt of the face on a new image.
I paste the face on to the seamless tile. I then clone brush (with a clonebrush set low, like 40 %) the outskirts of the face so that it maches the seamless tile i made and the face.
I then part by part paste the face onto the seamgiude for the face. There will be gaps and i use the clone brush to fill them, cloneing the neighbouring skin.
Hope that helped or gave u some ideas. I have never followed a tut, so there are probably much easier way of doing it, i just came up with this for myself.