Covering Skin Using Different Textures

I was a photo in a text book where a person's skin was completely swapped out by with another texture and I decided to take what I learned and see if I could duplicate it.  This goes right along with selections and is actually great practice considering this is one of the hardest things to do for me.

The photo I decided to start out with was this:

Once I was able to make the right selections (because thus far I have only made selections around landscape or windows) I followed the same instructions for swapping out backgrounds and instead swapped out the skin.  My first attempt did the trick but wasn't very interesting - jut merely a plain swap out.

But I soon learned that by changing the modes out of normal that I was able to get a much different effect.

This is shown in "Difference" 

This is shown in "Overlay"

This is shown in "Soft Light"