A patina on the surface, built up over many years and even with old marks and damage, is part of the character and value of a piece of furniture and should be preserved. If the surface is badly damaged and needs restoration, consult a specialist dealer for advice.
Waxing with a good quality polish based on beeswax (not spray polishes), brings out the colour and grain of the wood and provides protection. Put a small amount of polish on a soft cloth and rub the piece until the wax on the cloth shines.This will burnish the surface and evaporate any solvent. Then polish with a clean duster. If possible, apply the wax at night to allow it to nourish the wood and polish the following day. If the wood has become very dry, the wax will soak in rapidly and should be applied regularly until a good patina has developed. Normally, wax polish need not be used more than once every few months as too much wax will cause dullness and absorb dust. However, frequent dusting is important using a clean, dry, soft duster. This will encourage a hard skin to form which enhances the patina.
Brass mounts and handles should not be polished with metal cleaners which can harm the wood around them and remove any water gilding. A light burnishing while dusting should be enough to keep them bright. The gold finish on ormolu (gilded bronze) is very delicate and should not be polished. It should be handled as little as possible, as the acid in fingerprints can damage gilding, but it can be dusted gently with a soft brush.