The first thing you will need to purchase are shipping supplies. Baseball cards are light items so you likely want to choose the lowest cost shipping option. They are also valuable so you want to ensure they arrive safely. I recommend either buying penny sleeves in bulk to protect each individual card and toploaders or card savers to hold the cards. You’ll also need shipping labels, tape, and cardboard for support. Padded envelopes or bubble mailers work well for most orders. Boxes are preferable if shipping multiple high value cards or orders over 4 ounces.

Once you have the shipping materials needed, it’s time to package the baseball cards. Count out the exact cards being sold and triple check you have the right ones. Then apply penny sleeves if using individual protection for cards. Slide the sleeved cards into a toploader or card saver for added rigidity. For multi-card orders, layer cards carefully in the toploader without causing damage from excess pressure.

Consider how best to cushion the layered cards for the mailing process. Paper, air pillows or bubble wrap work well. Cut pieces to fit snugly around the toploader without being too tight. This prevents excess movement during transport. Now wrap the bundled toploader in tissue or acid free paper. Again, this adds an extra layer of protection from accidental bumps or impacts.

Assemble your cardboard or mailer. For boxes, insert crumpled paper filler to stabilize empty space then securely tape shut all openings except one. For padded mailers or envelopes, insert paper fill on the bottom and sides to support the bundled cards. Make sure there is adequate room without being overly loose.

Carefully slide the wrapped card bundle into the box or mailer through the open side. Double check orientation so the bundle does not shift during closing. Gently press in additional paper fill to minimize movement if needed. Then seal the last open edge or flap, securing well with packaging tape for a solid closure.

Label the package clearly with the buyer’s address plus your return address. Print shipping labels for boxes or affix stamps for envelopes/padded mailers under 13 ounces. USPS offers affordable baseball card rates. Consider adding delivery confirmation or insurance for higher value orders.

Bring the packaged, labeled order to the post office counter. Have the clerks verify proper postage and get a scan for tracking. Now inform the buyer their item has shipped with the tracking number. Prompt shipping after purchase makes for happy eBay customers. Proper packaging also means the baseball cards arrive in the described condition, avoiding negative feedback. Following these steps helps ensure a positive transaction for buyer and seller alike.

That covers all the key details needed for properly packaging and shipping baseball cards sold via eBay. Proper materials, careful layering for support and protection, secure sealing and quality labeling gets the valuable trading cards delivered safely to new collectors. Let me know if you need any clarification or have additional questions!