My normal technique is to apply a base coat of a yellow orange color, or a light wood color, then drybrush a darker brown over it.
Drybrushing is a technique that is falling into disuse these days. If you are not experienced with it, I recommend practicing on scrap plastic. I use a pallet of plastic coated cardboard, which I get from advertising flyers, especially now from candidates for election!
Dip the brush in the brown paint, only partially immersing it, and spread the paint on the pallet. Then clean the brush with a paper towel, and pick up a small amount of the paint on the pallet, and brush with medium pressure on the part that has been painted with the lighter coat. It takes experience to get the brush just wet enough. Move the brush only in the direction you want the grain to go.