I cant come paint your tombstone HJ. But I'll tell ya exactly how I did it.
1. I spackled all the cracks and sanded the whole stone.
2. Base coat of black Krylon H20, Its a latex water based spray and doesnt appear to eat the foam.
3. I used anitque white spray paint on the skele and skulls.
4. I then took small amount of exterior latex in the "irish mist" color from Home Depot. I pulled out the acrylic craft paints and grabbed the lamp black. I mixed about 1/2 cup of the latex and maybe a 1tsp or more of the lamp black. The color should be a medium gray.
5. I took a paper towel and wadded it up in my hand. Dipped it in the paint, and then scraped the excess off of the towel on a scrap of wood. I then began dabbing the towel on the surface.
6. I let that dry for maybe 30 minutes.
7. I took some yellow ochre acrylic craft paint and put some on a 1/2 inch flat brush and started to make the yellow tones on the skull heads and stone surface. Very light distribution mostly, a few areas I hit heavier like the top of the large skull. and also heavy on the skele.
8. Repeat step 7 with "irish mist"(white), and and then using a rust colored paint I did a very light distribution in a few select places (very light).
9. For the black below the large skull eyes I sprayed a good amount of black spraypaint in them then took a spray bottle of water and filled the eyes until it ran down out and down.
10. Final step. Light coat of poly urethane, then took some lamp black acrylic and added it to my bottle of water, so I had a very dark grey colored water.
I sprayed this over the entire surface, very heavy at the top so that the darkness ran down the stone.
Enjoy. I make this up as I go along. This entire process was done on the fly and I had no idea how it would end up. LOL