Lightly sand the entire surface of your piece to be treated. Be sure to sand with the grain of the wood using long, sweeping strokes.
Paint the entire surface of your piece using your oil-based paint. Be sure to mix the paint thoroughly before opening. Allow the paint to dry for 24 hours.
Shake and open your oil-based stain. Hold a paint brush in one hand and a rag in the other. Dip your paint brush in the stain and swipe a thin layer onto the surface of your piece to be finished. Immediately after making the brush stroke, swipe the stain with your rag. If you wait too long to wipe the stain, the paint underneath will become sticky and ruin your finish. Repeat the paint and swipe process until the entire surface of the piece has been coated. Allow the layer of stain to dry for 24 hours.
Repeat Step 3 as many times as you like. Each layer of stain will create added depth to seams, cracks, and veins in the wood, thereby increasing the aged appearance. Be sure to allow ample drying time between each layer of stain.