Things You'll Need
Instructions
Online Marketplace
Check each card's value in a baseball card pricing guide. There are two main guides to choose from, Beckett and Tuffstuff. Knowing how much your cards are worth will help you price it fairly.
Use a camera to take pictures of the card that can be showcased in an online listing. The pictures should show every square inch of the front and back of the card to give customers a clear idea of what they are looking at.
Make a listing on an online marketplace. Follow your chosen marketplace's instructions on listing your item. You will be able to set the price and add the photos along with a description of the card.
Wait for interested buyers to contact you about the card or purchase it. Notifications are typically sent by email. If the listing is not getting much attention, adjust the price of the card or edit the listing to help entice potential buyers.
Card Shop
Use the pricing guide to get an idea of the value of the card. Keep in mind, each card is worth only what someone will pay for it, regardless of its listed value.
Find a baseball card shop in your area that buys cards. You can use the Internet or the phone book to find the shop.
Take the card to the shop and approach a sales associate who works there. Talk with the associate about selling the card. You may have to negotiate the price, but if the card is valuable enough to the store, they will buy it for less than what they can sell it for.