If you have Citadel paints,a simple method is start with Bubonic Brown base.Then highlight with Bleached bone and then for your last highlight add Skull white to the Bleached Bone.If you wish a more gradual tone to the shade then just mix the stages together.(ie.Bubonic Brown,Bubonuc Brown/Bleached Bone,Bleached Bone,Bleached Bone/Skull White,Skull White for the fine edge.
If you use Foundry it\'s the same as above just use Boneyard a,b,c and white.
I hope this helps.
If you want it dirty looking just start with thined down Bestial Brown as your base and then use the colors in the order above.
Foundry Spearshaft a as the base and then use the process above.
