Should I clean my coins? The quick answer is always “no”.
A lot of people who are new to coins think they are doing good to get some ”dirt” off the coin by taking a jewelry cloth to it or putting some chemical on it. Although this can add ”shine” to the coin, that does not add value. It actually detracts from the collector value. Once you alter the original surface and luster, or the patina on a coin a collector will value it less. They prefer a ”dull” but original coin to a shiny one.
Think of it like art. There are professionals who can ”restore” a piece of artwork without damaging it, but you or I would never dare try to clean or restore artwork. The same is true of coins. They can be professionally restored, but when the average person tries to help them they often will do more harm than good. We have seen $100 coins turned into $10 coins really fast because someone was ”only wiping the dirt off”. If you want to keep your coins valuable, then keep them in the original condition. This is true of many collectibles, so before you clean anything, have them evaluated.