The short answer is, do not clean your coins.
WARNING - There is no way you can clean a coin without damaging the finish and reducing any collector value it may have.
Some coin catalogues suggest that you might use a soft brush on copper or bronze coins and, that there are professionals capable of cleaning coins.
Since you state that your coin is a collector coin, go with the short answer and do not clean your coins.
The best way to keep them is in some form of a protective casing or packaging to keep dust, moisture and finger prints off them. Most coin dealers will sell something suitable for storing your collectible coins.
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