If you are doing a still image and want to add some burning skins effects, this video will show you a quick 10 minutes way to do so. You start with a “blank face”, we chose a model on a white background, but any face will do.
To get the scorched texture we used a tree bark (from here) and to get the fire inside we used a fire effect from here. It’s a 7 minutes video, and by the end of it you will have a new tool in your photoshop arsenal.
If you wanted to see a quick step by step on how each step ads to the realism of the burning mark, you can see that in the animation below: