First of all, consider your colours. If you really want to make the wounds stand out, you should use the colour as an accent. Red is the colour of blood and pain, but also is a striking colour choice that can be used to enhance the intensity of whatever you’re trying to paint.
The problem is that if you use too much red on the rest of the image, or apply colours that are too saturated, the red of the blood is going to lose its visual strength. The solution is to use desaturated colours for the rest of the image, and limit the intense ones for the injuries.
In addition, try to achieve a gruesome texture. Think of ground beef with strawberry syrup. A natural look is important, so don't paint clean-edged wounds.
Portray splintered bones leaking bone marrow, torn pieces of flesh and skin hanging loose. If you're in doubt, search for photo references – although this might put some people off the topic completely!
Paco Rico Torres is a freelance illustrator living in Spain who’s produced art for several card games, magazines, books and role-playing games. This article originally appeared in ImagineFX (opens in new tab) issue 103.