Art alloy of tin, antimony, and copper, modem pewter (Britannia metal) resists tarnish and needs only an occasional wash in soapy water. Rinse the item well and dry it with a soft cloth.
Polish moderm or old pewter by applying commercial pewter cleaner as directed on the container. Or make your own modern pewter restorer: for matte finishes, mix a paste of pumice and water (a brighter matte), or rottens tone and vegetable oil (a duller matte); for shiny surfaces use automobile polish or mix a paste of powdered whiting and alcohol.
To maintain old pewter, just dust, then burnish with a soft cloth. The tin and lead in old pewter may cause it to develop a brown tarnish. A bath in washing soda may help to remove this. Because of the lead, don’t eat or drink from old pewter utensils.