im not sure about others, but ive always had trouble with wood. Id try to take the cheap way out like noise efects, and it doesnt work most of the time. well i found this great tutorial on it at this excellent pixelation website called zoogles.
http://www.zoggles.co.uk/asp/tutoria...?tut=4&page=12
here is mine after following the tutorial. and i only used 6 colors! very easy too.