Instructions
Get a copy of a price guide such as "Whitman's Red Book." The best guides are usually updated annually and contain pictures and descriptions of rare and unusual coins like double-struck coins.
Look up your coin in the guide. Because these coins cannot be accurately graded due to the printing error, you will usually one see one price for a double-struck coin. Older coins of this type tend to be worth more. For example, a recent Jefferson nickel will usually list for less than $50, while an Indian head penny is valued at a few hundred dollars in 2010 prices.
Assign more value to the coin if you can see a date. Multiple strike coins where the date is visible are hard to find, making these error coins worth a slight premium to collectors.
Give the coin a higher value if the coin has more than two strikes. Whitman's says the value increases with each additional strike on the coin.