What is the best way to store collectible coins so they will retain their value?

There are special cases made especially for storing coins. The fancier version has a clear top and a soft lining inside with an impression for the coin to fit into. Sometimes it's foam, sometimes it's a velveteen type of lining. The cases are very thin, maybe 1/2 an inch thick. A lot of coin dealers sell these on the internet and you might even be able to find a place where you can buy them wholesale, if you have a lot of coins. There are also little envelopes made if you wanted to go a cheaper route. They are manilla type, sometimes white, sometimes ecru or another color and they have a clear plastic window so you can view the coin. Then there are larger versions: like if you have a lot of old pennies for example...these cases are folder type cases that usually have more than two sides, some have three. They have a strong cardboard or other type of strong material for the outside cover and will open up into sections; two, three or sometimes more. Often the dates are printed in on them so you can place the corresponding coin in the correct place so they are in order by year. There are other types of storage for coins but the above are usually the most common. After all, I think you know this already: you want to store them so they do not rub together and cause more wear by friction (like storing them in coffee cans, etc.) Whatever you do DON'T clean your coins. Coins are one of the collectible items that lose value when they are cleaned. And if you have a lot of uncirculated coins, use extra care in handling. Body oils can cause damage and often, when a coin is uncirculated and you wish to sell it later collectors will be looking for mint condition, no damage, scratches, etc. If they are not already in a case (which is usually the way the special coins are stored and sold to consumers), it's probably best to use latex gloves (or the alternate version if you are allergic to latex. That way you won't have to worry about any body oil contaminating your pristine coins.) Hope this helps!! There are many products available from coin dealers to preserve your coins. There are the paper envelopes, 2x2 cardboard and mylar holders, and a myriad of special plastic cases. The main considerations are to use only acid-free products and minimize exposure to sunlight, heat, and air (and of course to minimize any handling). One thing to remember - when the coin is sold, you will not get any extra for the holder, so it is not economical to preserve a coin worth 25 cents in a holder that costs four or five dollars unless you expect its value to increase dramatically.