Coin dealers are eager to buy old coins from uninformed sellers. They can often pay a low price acquiring coin collections from naive relatives of a dead collectors. Coin dealers then turn around and sell the old coins for a big profit. It is important to be knowledgeable about coins you sell to a coin dealer. If you know what the coins are worth on the open market, you can demand a fair price from the coin dealer.
Examine each coin you want to sell to a coin dealer. Write down the denomination, year and mint mark. The mint mark is indicated by a small letter, usually near the date. Some coins do not have mint marks.
Grade each coin's condition. If it is bright with plenty of mint lustre and no wear on the details, it is an uncirculated coin. If the surfaces are dull but contain most of the original details, the coin is in the fine to extra fine range. If some of the details are worn down it is in the fair to very good range. Coin grading is subjective, but knowing the grade range will help you determine its approximate value.
Look up the coin values. Check the references section below for several sites listing coin values. Use the different listings to determine a price range for each coin. Notice that the price of each coin can vary significantly based on the coin's condition. Write down the value of each coin for the highest and lowest condition you think is possible.
Add up the high and low values for all the coins you want to sell to a dealer. This will give you a range for the value of entire collection of coins. Expect a coin dealer's offer to be toward the low end of this range. Keep your list of individual coin values. Coin dealers often want to "cherry pick" collections and only buy the best coins. Decide whether you are willing to do this or will only sell the entire collection together.
Shop your coins around to multiple dealers. Do not fall for high pressure tactics. If a coin dealer says their offer is only good right there and right then, they are probably trying to low ball you on something valuable. Legitimate coin dealers wont mind if you entertain multiple offers.