Would say that you are half way there. Go to a coin shop,& P/U E Zest Coin cleaner,& a large set O plastic tongs,& slot the edged to be able to hold the brass,by the edge only,& dip quickly into the E Zest,& rinse Strike intently,with Water. Take baking soda,& dump some into your palm,& make up a paste a rub the rim gently,thoroughly. it will not scratch the Brass. Rinse thoroughly under Water. Pat dry with a paper napkin,without rubbing,& set aside to make sure it is completely dry. The Brass will then not Tarnish,as previously. Have done this for years,always works for Me.
John