Depends on how bad the damage is but small dents and scrapes can be rubbed down with a bit of fine abrasive (emery board is ideal) and touched up with a bit of clear nail varnish. More serious gashes can be filled with a matching filler such as Plastic Wood- just be sure to use the solvent based one that comes in a tube (their water based filler is rubbish) This dries hard and can be sanded and will look as good as the original wood as long as the right shade is chosen. Again touch up with clear nail varnish(on smaller repairs).