Things You'll Need
Instructions
Classification
Classify your coins according to country of origin and denomination. This information is usually found somewhere on the coin itself. If it is not, you may need to do some research. The best place to start would be your local coin shop.
Find the year the coin was minted. This is usually on the front of the coin, but sometimes it appears on the back. Roman numerals are occasionally used to mark the date on coins.
Look for mint marks. Some coins have marks that designate the specific location at which they were minted. This mark can greatly affect the value of a coin. Different types of coins have mint marks at different places, so make sure to thoroughly check both sides of your coins.
Grade your coin. Every coin has different criteria upon which it is graded, so you will have to read up on the specifics of your particular coin. This info can be found in most price guides. The grading for circulated coins runs from "about good" to "uncirculated."
Value
Buy a price guide. There are many quality coin price guides on the market, like the "Blackbook Price Guides." These guides can be found in almost any coin or book shop.
Look up your coins in the price guide. Make sure you are taking all of the coin's factors into account when doing this.
Take any especially valuable coins to a dealer to be professionally graded and appraised. By doing this, you will find out the exact value of your rarest coins.