I pretty much use corn cob media I buy in bulk for cleaning and polishing everything,my brass never really gets dirty other that some powder burn residue. I mix a couple cap fulls of NuFinish car polish in with ever new batch of media and let it work in before adding the brass after that I just add a cap full every three or four batches of brass if its needed. A couple strips of used dryer sheet added to each batch of brass will help keep the media cleaner longer. I tumble about 30 min. before resizing and 30 min after to remove any lube on the cases before loading.
For weathered/tarnished/powder burned brass you can use a product called Lemi Shine. I get mine at Wally World,just mix one lever teaspoon per quart of HOT tap water in an amout to cover the brass and let the brass soak for 30 min. stir or shake the brass in the container and let soak another 30 min. then rinse with clean water and let dry before tumbling. It will clean the brass inside and out and after tumbling it will look good as new.