said somewhere:
For a dark wood black with a dark brown over it would work. Or if you start with gray and a bit lighter brown you would get something a bit different. Also if you did a very light red in there some where it might come out like cherry wood. Pine planks always looked a bit yellowish too me so maybe a dull yellow over a light tan. So I guess I would say just find a kind of wood you like the color of in real life and try too match it.

In this forum someone said:
Little tip for you when painting eyes. Basecoat the face but leave the eye sockets black. apply your wash. Take a fine detail brush and instead of trying to paint the whole of the eye in white and adding black pupil afterwards which is incredibly difficult to get the two pupils to look the same way try this. in each black eye socket dot a tiny dot of white into each corner of each individual socket it doesn't matter if the dot overlaps the socket above or below but concentrate on leaving the black pupil in the middle (this is the area you don't want to have to touch up) If the white overlaps above or below the socket use dark flesh (doombull nowadays I believe) to touch up around the white. Once your happy highlight the face as normal.

PVA, brown/green, a few water until it becomes a bit fluid, very few gloss varnish. Encircle the base with a tape and pour inside. After it dries use dark green/blu wash.

Add water to balsa wood and twist it with your hand