Very simple to do, very quick. You can do 3 in 30 minutes this way.
1.Undercoat model white.
2.Water down some Citadel Glaze Waywatcher Green. About 3-1 ratio water to glaze.
3 Apply in several thin coats trying to be as smooth as possible. 3 layers should do tricks. At this stage keep gravity in mind when glaze is drying, try not to allow heavy pooling of coloured glaze.
4. Hit the recesses carefully with more than the surface areas.
5. Spray very gently a thin white on top from above (can use airbrush or undercoat white spray from distance.
Spooky job done!