What is the best way to clean and shine dirty brass?
Depends on what it is & how big a job it is. Lots of ways to go. A goog cleaning with paint remover will get rid of organic crud & old finish if any. That alone can to the trick & wo’nt destroy the patina. If it is really bad, a buffing wheel & rouge may be necessary to cut through the oxidation. The acid cures like, citrus & vinegar work ,but may cause the brass to go pink in which case buffing or abrasive cleaners like brasso might be way to go if you want a bright finish. Auto polishing compound (white) will give a softer shine will leave some patina if that’s what you want.