would this be for fondant or cooked sugar? or something else?
Definitely use yellow and brown. But, I'd start with yellow. Much easier to go darker than lighter. Of course, that could just be me, I've been known for impatience and just want to get to the right color fast. 
Yes, what analon said. If you don't have brown coloring to begin with there are several other ways to get there. You could start with a yellow orange and add a really, really tiny touch of blue. What do you have to work with as far as colors go?
For painting, I would start with a golden fondant and then paint it with a thin, translucent coat of brown.
Just a tip on the color brown and what shade you may end up with. If you've ever played with fondant, colored with Wilton... when using a tiny amount of brown, you'll get a great flesh color, slightly pink. Reason... brown is made with complimentary colors... red and green are complimentary. Wilton's brown has more red than green. Most browns lean towards the red side. If you mix the complimentary colors of orange and blue, you may get a more green brown. This is due to orange is made with a mix of yellow and red, therefore the red is diluted. Yellow and blue make green. So... mixing orange and blue will give a more green cast to your brown. Cake Kraft brown uses less red and I've never used Americolor, so I don't know how there color compares in regards to the amount of red.
artscallion's idea of painting over a golden fondant would probably look great!
Sorry, don't mean to go on about the color wheel, but I find colors fascinating!
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