There was a nice tutorial on Uruk-hai on the GW site before they decided that they should charge money for such things (as if painting an army wasn't expensive enough already). It was a bit of an eye opener for me when it came to browns as they mixed in grey to highlight it. So perhaps a combination with marell's tip?
Also, unless the entire miniature is brown I think it's a rather neutral color that the eye isn't drawn to so it doesn't matter if you do it quick and easy, especially on a base. One of the Blue Table Painting artists, sorry for not recalling which one, also has said that if the miniature is bright the base should be dark and vice versa. Personally, I find that the only capital failure is dark miniature on a dark base but opinions may vary. As we say in Sweden (for the benefit of everybody else reading this); taste is like the bum, divided.
