Put on rubber gloves. Clean the kick plate with a wet soapy sponge. You can just use regular dish soap on the sponge.
Rinse out your sponge and wipe it over the kick plate to rinse off soap. Dry the kick plate with a towel.
Apply metal polish to a clean cloth. Use a polish that states it is safe for the metal you are using it on.
Rub the polish into the kick plate, using even back and forth strokes, covering the entire plate. If the metal has a brushed metal finish, make sure you polish in the direction of the grain.
Buff the kick plate with a dry cloth until the plate shines. You may need to apply metal polish more than once, and rub it in, if the piece has been neglected for some time