I always use gloss nail polish for the final coat on gore. A base coat of black/dark green, then dry brushed over with red and pink is what I've been doing lately (the darker undercoat gives more contrast). A fellow sculptor recommended using red ink, tinted a bit with green, rather than paint, for blood, but I've yet to try it.
lol. I made casts of an upper body from a RE Krauser I had and the wounds are actually part of the sculpt. I'm doing a 3-4 coat approach. the base is gameworkshop red gore, then scab red, and then blood red for the highlights. I have their chart on what is the base, shadow, highlight of their colors and it's helped.