I found this out when I painted an M-1 Garand in 1/6 scale. Paint the item in whatever brown base color you want (dark brown, light brown, etc..). Invest in a set of Windsor and Newton oil colors (they should last forever, they come in complete sets that should cover most colors). Take a wide bristle brush, set it in either the burnt umber color, or another color that will contrast (like a tan, or light brown) and pull the brush along the item. It leaves convincing lines, and since the wood used was usually high quality, you dont have to worry about knot holes in the wood. It also leaves a realist raised panel from the paint, which gives it a wood feel...try it a few times, it works great