Well, for starters, I do not like "BRASSO", although I recently read about a combo of brasso and something else but brasso leaves too much residue for me. I DO like "NEVER DULL" "magic wadding polish". I take a very small finger tip pull from the can and let it set a while to dry out. The cleaning agent will sort of dry up and while it still cleans it "flakes" off rather than clogging up the detail. I also like to wipe it off completely and then go over the brass with a "field wipe" as those made by Remington or other common brands. That seems to protect the brass from tarnishing for several outings.
I honestly like the color that old brass takes on over even a short time but what I do not like is some of the spots that seems to show up. I think they are due to some direct contact with powder/fowling matter?? If I could achieve an overall even dark color that would be fine but for now and because I want to maintain them that way, I'll keep the brass bright.