How do you look up information about rare coins?

There are many sources (I'm citing mostly U.S. references here).

If you want books, visit your local library and ask if they have the Whitman "Red Book" or one of the Krause guides to U.S. coins. These are good starting points because they have history, facts and figures, and approximate retail values.

There are also loads of online resources. Check out CoinClub.com which has links to lots of other sites and many FAQ's, CoinSite.com (a bit out of date but again, many links), CoinFacts.com for pictures and mintage figures, plus the sites of the major numismatic organizations - PNG, Numismedia, PCGS are 3 that come to mind.

Be aware that rare coins are a rarefied subject (pun intended). As someone starting out you'll only be able to come up with rough estimates of coins' values if you suspect any you have are rare. There are many subtleties in grading - and at least as many differing opinions as well - so if you have any high-end coins appraised you should get 2 or 3 different evaluations. A dealer will always pay less than retail for a coin because they have to make a profit, so don't be disappointed by an offer that's 25 or 30 percent below what you might see in a book.

You can also go the eBay route and make more, but you need to really keep your guard up and have your coins graded and certified. Despite all the decent, honest people who sell there, I've seen a disturbing number of posts with overly-optimistic asking prices, ignorance (e.g. those "rare" Lincoln-Kennedy cents*), and just plain deceit.

(*) NOT!! They're novelty items made outside of the Mint and worth a couple of cents, if that.