I wouldn't use brasso because chances are it leave behind a residue which is a no no.
It's best to use a piece of glass since it's perfectly flat to sand on.
You need varying grits of sand paper starting at 800grit, working your way up to 2000grit and/or 10 micron sand paper.
It takes quite a while per sheat and using water during the whole process is better. Wet sanding is always better than dry sanding plus will wash off the build up of metals.
Then if you can get ahold of some, while finishing up with the 10 micron paper use some 10,000grit polishing compound. This will basically bring it to mirror finish