Sand the furniture with 120-grit sandpaper. Pay special attention to areas such as the top of doors and the area around knobs and handles. Use the sandpaper to make edges rounded, too. Wipe the sanded furniture with a dry cloth to remove sandpaper dust.
Add marks and scratches consistent with old furniture. For example, you could dent the furniture's surface with the edge of a heavy pan or scratch it with keys. You also could burn the furniture slightly with cigarettes or spill ink to make an ink stain.
Apply black spray paint to the bottom of a can. Press the painted can against the furniture's surface to simulate water rings.
Stain the furniture's wood with a golden or other light stain to make it appear as if it was overexposed to sunlight.
Apply tung oil to the wood. It will help to preserve the stain and antique appearance without making the wood appear glossy.