Most of the polished aircraft that you see usea polish called Nuvite, which comes in several grades to progressively build up the level of polish. Involves many, many hours work on an airframe; maybe not so much of an issue for you.Progressively refining the polish grade after removing all traces of the previous grade is usually the way to go.
Google lapidary suppliers for graded carborundum pastes and cerium oxide polish.
I think sulphur is more of a problem in polishing lower grade alloys.