"Never be induced to pay extravagant prices for worthless coins. There are some coins which command and are worth a large price. But these are, in fact, very few. Even the rarity of a coin is no test of its real value to a collector. It may increase the price of the article; but the young collector should bear in mind that the high price asked for a coin because it is rare, ought not to make him desirous of possessing it. The moment that the collector begins to value coins because of their rarity, he descends in the scale of Science; and when he seeks to possess rare coins merely because of their being rare, he becomes a speculator, envious and uncomfortable in the presence of others, and ceases to be a genuine Numismatist.
Read as you collect. Never let a coin lie in your cabinet that you cannot give the history of, or connect with some historical event if it be possible. Be careful that your collecting does not become a mere matter of curiosity. Let it rather be a constant aid to your study."
from The American Journal of Numismatics