The Jefferson nickel was introduced in 1938. With the exception of a few oddities, most Jefferson nickels are not very valuable. Pre-1938 nickels, called Buffalo nickels or Indian Head nickels, and pre-1913 nickels, called Liberty Head nickels, are far more collectible.
Determine which coins you already have
Sort through your coins. If you find any older nickels, especially any Buffalo or Liberty Head nickels, set them aside. Numerous books and websites can help you determine whether a coin might be valuable.
Decide which coins you want
Finding valuable coins by chance is a rare occurrence, so if you are serious about collecting, you will probably end up buying coins from coin dealers. Use guide books or websites to decide which coins you want and how much you can expect to pay.
Do your research
While most reputable coin dealers are not out to cheat customers, they are in business to make a profit, and most expect the consumer to be informed. The more knowledgeable you are, the easier it will be for you to recognize a good price when you see it.
Do not wash or polish your coins
Cleaning and polishing is one of the best ways to reduce the value of old coins. Professional coin dealers are adept at spotting a cleaned coin, and will not be fooled just because a coin looks shinier.