Guitar polish: spray on a cloth, clean any dirty areas and polish with a dry cloth. This formula protects the instrument by a wafer-thin non-smeary gloss and is harmless to all varnished and waxed areas, suitable even for most historic instruments.
Fingerboard oil can be used every time the strings are replaced and have already been removed. Moisten the fingerboard thoroughly, allow the oil to soak in for a while and rub off the excess oil carefully. The oil removes dust and dirt, prevents the wood from becoming brittle and reduces cracks.