I second tales' suggestion on Wright's. Their brass polish is safe for brass, copper, chrome, bronze, and pewter. It works really well as does their silver polish for silver & silver plating. This line was recommended to me by an antiques shop owner and I am so glad he introduced me to it, I use it on my "keepers". Just remember that with their brass polish you have to rinse it off well afterwards so it doesn't leave any white residue behind.
Also--at least in my neck of the woods--they have it at most grocery stores in the furniture polish & cleaners section.
I also agree with mart though that there's a possibility it won't all come off. I have some copper pots that have some wear that won't go away, but I love them just the same! Good luck!