The first step is to set up your eBay seller account. Go to the eBay website and click on “Register” to create a new account. You will need to provide your name, address, email address, and create a password. Read through eBay’s user agreement and complete the registration process.

Once your account is set up, you will need to collect the baseball cards you want to sell. Go through your existing collection or visit local card shops, card shows, or garage sales to find cards. Make sure any vintage or valuable cards are in good condition without any creases, folds, or damage. Condition is crucial for older cards. You may want to have valuable cards professionally graded by companies like PSA or BGS.

Now it’s time to photograph your cards. Take detailed, high resolution pictures that clearly show the front and back of each card. Make sure the images are clear, in focus, and brightly lit without any glare or shadows. You’ll want buyers to easily see all details of the card. Invest in a lightbox or light stand to take consistent pictures.

When creating your eBay listings, be sure to use accurate titles that describe each card. Include the player name, year, set, card number if applicable. For example: “1994 Upper Deck Ken Griffey Jr. #328.” Write detailed descriptions noting the card condition, any flaws, and include the picture links. You can also mention any relevant details like if a vintage card has been graded.

Pricing your cards correctly is important. Research recently sold listings on eBay to get a sense of fair market value for each card based on condition. You may need to price slightly below recent sales to attract buyers in a competitive market. Consider offering calculated shipping rates or free shipping promotions on multiple card purchases.

List your cards with an appropriate duration, usually 7-10 days for standard auctions or 30 days for fixed-price listings. The standard listing fee on eBay is usually the best option. Make sure to formally end auctions rather than relisting if items don’t sell.

Promote your listings on social media sites frequented by collectors. Encourage friends to share your auctions too. Consider running periodic eBay “bucks” promotions where you offer a partial refund on orders over a certain amount. Interact positively with any questions from potential buyers in your eBay messages.

Package cards securely in penny sleeves, toploaders or magnetic holders before placing in rigid shippers or boxes with bubble wrap lining. Record sender and recipient info directly on packages rather than loose paper inside. Purchase tracking on all shipments through your eBay sales record. Promptly ship within 1-3 business days of sale.

Provide excellent buyer service. Quickly reply to questions, honor refund/return guarantees, and leave positive feedback once transactions are complete. Poor feedback can significantly damage your seller ratings. You may also want to diversify your sales across additional platforms like COMC or auction sites like Heritage Auctions.

As your sales increase, you may need to upgrade your eBay seller limits or explore other inventory and shipment solutions to scale your business. Continually improve your photography, listings and promotions based on buyer analytics and industry trends. With consistency and experience, selling sports cards can become a viable part-time income or even full-fledged business on eBay with the right approach. Starting small and focusing on buyer service is key to long term success in what is a very competitive marketplace.