How To Identify Potentially Valuable Sports Cards

Here's How:

1. Condition is critical. If the cards aren't in good shape, you can probably skip right past the rest of these steps. Vintage cards can be held to a lower standard, but if you're seeing a lot of creases, bent corners and the like, you're not looking at something worth much money. Even the most desirable cards of the hottest players are no good if they're in poor condition.
2. Age matters, so check to see how old the cards are. Many of the collections that walked through the door of our store were from the early to mid-90s, when the card companies were cranking out tons of cards. Today, most cards from that era aren't worth much. If the cards are older (especially if they are pre-1980) or current, you may want to investigate further. Some cards have the year they were made somewhere on the front; for others, you may have to check the copyright date on the card back. Even common cards from some vintage sets can bring some money, so be sure to keep an eye out for older cards.
3. Autographs are always good. There's a market out there for all but the most obscure players' signatures, though that doesn't mean you're going to break the bank with most of them. Authentic autographed cards certified by the card companies are a relatively recent development, so be wary if you find older signed cards. Chances are that these autographs, even if they are legitimate, won't be worth much to most collectors because there is no way to know for sure if they are real.
4. For memorabilia and jersey cards, the older the better. Products released in the past few years have flooded the hobby with single color jersey swatch cards, many of which are a tough sell. Jersey cards from 1999-2000 have held some value because they were still a new phenomenon back then. Of course, if the memorabilia card in question is a multi-color patch card numbered to three, it doesn't matter what year it's from - you should add it to the potentially valuable pile.
5. Rookies rule the hobby, so they're always worth seeking out. The trick is to identify them without a price guide, and it's not always easy since some cards that say rookie card on them actually aren't. Your sports knowledge can sometimes help, as in a lot of cases (especially in football and basketball) a player's rookie card is from his rookie playing season. When in doubt, assume the card is a rookie and look it up later to find out for sure.
6. When all other things are equal, supply and demand takes over. Check to see if any of the seemingly innocent looking base cards might secretly be rarer parallels. You probably won't be able to identify cards which are simply short-printed unless you're very familiar with the set they're from, but serial-numbered cards are always recognizable. Print runs of 25 or less are generally the cut-off for turning otherwise uninteresting cards into items with some value.
7. Stars shine in almost all circumstances. Base cards or garden variety inserts can sometimes be worth something if the right person's picture is on the front. Expect cards of a sports's biggest stars - think Michael Jordan, Babe Ruth level here - to interest a collector somewhere in most cases.

Tips:

1. Remember that these are only guidelines for picking out potentially valuable cards at a glance. Your best bet is always to look up the card in a price guide, check online sale activity or ask a dealer if those options are available to you.
2. Even some cards that don't have immediate value may be worth holding on to in the event that they increase in desirability somewhere down the road. Rookies of players who are still active definitely fall into this category, as every new sports year brings a few unexpected breakout players.
3. As with all things related to the value of sports cards, actual value is determined only by what somewhat else is willing to pay. Always keep that in mind.