Most wants will be some shade of brown, but the Harry Potter movies also had wands that were white or black. You can even paint your want different shades of one color to make it look more like wood. Consider using watered-down acrylic paints if your chopsticks are made out of bamboo. This way, the original texture still shows through. Take the darker shade, and use it to fill in any nooks and crannies on your wand. You can use a q-tip or a pointy brush to get to those hard-to-reach areas. Then, take your lighter shade, and use it to highlight all of the raised areas. If your wand is black, you will only need the highlights. If your wand is white, you will only need the shadows. Bring the wand outside and set it down on a sheet of paper. Spray it with some clear, acrylic sealer, and wait for it to dry. When the wand dries, turn it over, and spray the other side. Repeat this step, if necessary.  Sealing the wand is not absolutely necessary, but it can make the paint job last longer. You can use a matte, satin, or glossy finish.

Summary:
Paint the wand a base color using acrylic paint. Add some weathering using lighter and darker shades of your base color. Seal the wand with a clear, acrylic sealer to make the paint last longer.