Put on your safety glasses and dust mask. Sand the oak furniture towards the grain with 120 medium-grit sandpaper until you reach the bare wood. Continue sanding until the surface is smooth with no splinters. Wipe the furniture down with a tack cloth.
Poke small holes into the surface of the wood with an ice pick to create marks that appear to be signs of insect damage. Hold the ice pick at an angle to create longer divots in the wood. Dip a toothbrush into black ink. Lightly brush over some holes to create small, darker spots that look like damage.
Brush on paint or stain with a paintbrush on a small area. Let the paint or stain rest a few minutes without drying, and then wipe some of it off with a cloth. Move on to the next small area on the furniture, painting or staining it and wiping it off until you have covered the entire piece of furniture. Let it dry for about 24 hours.
Hit the piece of oak furniture on the sides and top with a 2-foot long piece of heavy chain. Continue hitting the furniture until you have created dents and bare spots on the wood finish. Hold the chain at both ends, and rub it back and forth across legs, corners or crosspieces on the furniture.
Sand any darker painted or stained areas with 120 medium-grit sandpaper. Sand down some of the corners, straight edges and carved areas to create a worn appearance. Wipe down the furniture with a tack cloth.