Clean the tin as much as possible using a solution of hot water and dish soap, scrubbing with a plastic-bristle scrub brush. Use pipe cleaners to get into the punched holes. Rinse and dry the tin thoroughly after you are finished cleaning.
Remove tarnish by spraying the tin with tarnish remover and buffing the tarnish away with a soft, dry towel. Tarnish remover also will remove light rust. Light rust also can be removed by scrubbing the affected areas with vinegar.
Eradicate heavier rust by treating the affected areas with automotive rust remover. Coat the rust with the remover and allow it to sit for the time indicated in the manufacturer's instructions. Rinse and dry the tin thoroughly.
Spray the tin with a coat of clear metal sealant to protect it from future corrosion. Hold the nozzle of the can 10 inches from the surface and spray in quick, sweeping, overlapping motions. Be careful to not allow the sealant to pool or drip. Allow the first coat to dry to the touch and then add a second coat.
Buff the tin with metal polish, using a soft cloth, after the second coat of sealant has dried.