Okay this is my first how to so be kind....
Some supplies that you will need:
Binder (or what ever else that you want to skin)
Cotton balls
Paint and or stain
Brushes
Latex
Clear nail polish or clear epoxy
Once you have gathered up all of your supplies take some cotton balls and start to unroll them. How many you need depends upon how big your project is. It is better to unroll to many than not enough. It gets kind of hard to unroll cotton balls with wet latex on your fingers...you'll see.
Now that you have your cotton strips laid out and ready you can start dipping them in latex one at a time. Lay the strip in the latex making sure that the latex soaks in then pull the cotton out. Let the excess latex drain back in your container then place the soaked cotton onto the binder. When it is placed on the binder slightly spread it out with your fingers. Do not over stretch the cotton or you will have blank spaces on your binder. When wet it looks like you've got good coverage but after it dries...well you'll see.
To make good looking skin you will need to bunch up bits of the soaked cotton with your finger tips this will make pits and valleys across the surface that will add depth to your sick masterpiece.
Okay now just let it sit and dry. If you put a fan blowing on it it dries very fast. well not very fast but if you do this in the morning you should be ready to paint that night.
Once dry start painting. I use stain on it first. I brush it on let it set for a few seconds and then dab it of with a rag. Then I take a darker shade of acrylic paint and kind of dry brush areas then follow up with a light dry brush of a lighter color over the entire thing.
For blood I mix blue and red paint and paint some of the valleys with a fine brush to get detail. After it dries if you want a wet look cover the blood with the clear nail polish or clear epoxy.
You can do this technique to just about anything. one thing that i would like to add is to finish the inside covers of the book you can take felt or fabric and hot glue it so that the binder cover does not show.Also if you put baby powder on the latex that drips onto the inside cover it will keep the binder from sticking together when you close it.
Hopes this helps.