If they are valuable or collectable take them to an appraiser or coin expert for advice. You can take the value away if cleaned incorrectly.
Tooth paste, the original kind with no gel or anything added works well on all metals.
Brasso would probably work to clean the coins... I hope this helps!
Here is information on using toothpaste to clean them https://chemistrycachet.com/how-to-clean-your-house-with-toothpaste/