1- If you don't know its value, don't clean it, or if you think it is valuable, don't clean it, or if you know it is valuable, don't clean it. In other words, do not clean your coins never never!
2- The coin should be protected from exposure to any kind of elements, by this way you can brotacet your coins.
3- It is also important not to scratch the coins.
4- Coins should be cleaned properly using lemon juice, or alcohol.
5- It is very important to remember that the value of the coin .