What Steve said but I would stain the bow first then apply the skins.
I use a natural stain on my hickory bows of the outer hull of the walnut. These can be collected when the walnuts first drop and the hulls are green. Just crush the hull and in a matter of hours it will turn black and can be soaked in a can with water to get the stain. Just keep applying as Steve mentioned to get it darker. For really really rich color use the fresh green hull and rub directly on the wood. Wear gloves or you will stain your hands and it will not wash off.