Fingerbox /b/ros, how em off if you got em

I finally got my antique finger box delivered! It took nearly 4 months to get it through customs, but I got a great deal at auction. It looks kinda fragile, but it has some serious heft to it. It's not as fancy as some of the ones they had up for bid, but it's still the nicest one in my collection. Any advice on keeping the brass from tarnishing without wrecking the patina?