Thanks, everyone...
And Warren: Here is how I do that wood.

I just start with an overall light tan color and then mask off areas that I think were different panels just to add variety. These are sprayed with various shades of the original...both lighter and darker. After that it looks kind of dumb with too much contrast and like a patchwork quilt.

Then the fun starts...I just use raw umber oil and stipple it on in tiny specks with a brush or foam piece...whatever makes it look sort of random. Then I come back with a soft, broad brush that was dipped in thinner and wiped on a towel (so it's not super wet) and very gently go over the spots. I can pull them various ways, twirl around and keep playing with it until I get the right look. Then I give it some depth and a bit of color with a varied coat of clear orange. Kind of makes it "pop". It's fun to do.
As long as the base coat is acrylic, there are no worries and you can make lots of mistakes too.
Thanks for asking. Give it a try!
Dan