What it really comes down to what coin YOU want to collect. Any coin you find interesting is worthy of being collected. There are no hard, fast rules about which coins are collectible. Do what you want, how you want, and have fun doing it!
There definitely is a career in it IF you are very educated in all series. Being a dealer is considered a professional occupation. So make sure you know your stuff before you open shop, or online store. People come to you asking about the value of their coins quite often, and you are expected to know the answer, and offer them a fair value.
So assuming you have years of experience (which you must not, seeing as how you asked if there was a career in it) it is possible to make a career out of coin collecting.
For the collector value of any coin to be determined, you need to advise the country of origin, the type of coin, the date and the condition of the coin at the least.
DO YOU BUY OLD COINS
Go to the coin collecting sites to ask
numismatist
A coin collection is called, well, a coin collection. The hobby of collecting coins is called numismatics.
a coin collector
Coin collecting
While the president has not said much about coin collecting, he has said a lot about education and about the importance of hobbies that are educational. Both stamp collecting and coin collecting teach about geography and about important historical figures, so the chances are, he would be in favor of such hobbies.
Numismatology
Coin collecting
RPM is a coin collecting slang for "Repunched Mintmark". It refers to when the mintmark on a coin has been struck twice, and you can see remnants of the first mintmark underneath the second mintmark.
Lots of wear on the coin and the lowest grading possible.
edge of a coin with grooved lines that run around the entire perimeter of the coin
In coin collecting, it means Brilliant Uncirculated, a very nice coin, but not as good as a Proof coin.
Burton Hobson has written: 'Coin identifier' -- subject(s): Coins 'Coin collecting as a hobby' -- subject(s): Coins, Collectors and collecting, Juvenile literature, Numismatics 'Stamp collecting as a hobby' -- subject(s): Stamp collecting 'Historic gold coins of the world: from Croesus to Elizabeth II' -- subject(s): Gold coins 'Illustrated encyclopedia of world coins' -- subject(s): Coins, Dictionaries, Encyclopedias 'Picture guide to coin conditions' -- subject(s): Numismatics 'Hidden values in coins' -- subject(s): Coins 'International guide to coin collecting' -- subject(s): Coins 'Stamp Collecting for Beginners' 'Getting started in stamp collecting' -- subject(s): Stamp collecting 'Coins and coin collecting' -- subject(s): Coins 'Catalogue of Scandinavian coins' -- subject(s): Scandinavian Coins
A coin described as "Premium Quality" is an above average example.