You have a lot of options when selling your football cards. Online forums and auction sites, such as eBay, may help you to make quick sales. But you may not get the full value of your card, depending on how the bidding process goes.
It’s often better to take the selling process slowly. Have your card graded and evaluated by professionals, such as those at Bleecker Trading. It also helps to build a network of fellow collectors and investors because they may be able to point you to buyers who really want your card. An incentivized buyer will tend to offer more than somebody buying online, especially because they get to see the card in person before handing over their money.