For the green I used Panzer olive grun, just like the ESB helmet. I thought it came out pretty good. I used a silver base coat, then the Grun. i tried rubbing the green off to expose the silver but I kept going down to the plastic so I brushed some silver over these areas to highlight the damage. For the black marks I used a black crayon, marked the areas and then used a sweaty finger(sounds funny but it worked)and blended the crayon in a little.
If you need anymore color help let me know.