Dusting frames and glass (if any) should be done with a soft lint-free cloth. Be careful cleaning styrene glazing it can scratch easily, always use a soft lint-free cloth. Never clean gilded frames with a damp cloth, detergents or sponge as this will eventually remove the gold leaf. It is recommended that frames be dusted only with a soft dry paint brush.
Picture cleaning should only be done by a skilled professional.
Stains and foxing on paper can also usually be dealt with by a paper conservator.