How to Safely Package Cards and Memorabilia Before You Ship a Sale
Good packaging prevents the problem, not just insures against it
Once your card or memorabilia sells, how you package it for shipping matters as much as how you priced it. A well-packed item arrives the way the buyer expects, which means fewer disputes, fewer damage claims, and a smoother sale overall. This is about prevention. If something does go wrong despite good packaging, that's a separate question with its own answer, covered elsewhere.
Packaging a single card
A raw (ungraded) card should go in a penny sleeve, then a rigid top loader or card saver, to protect the corners and surface from bending. Slide that into a bubble mailer, and add a piece of cardboard or a top-loader-sized rigid insert on both sides so the card can't flex inside the envelope. A graded card in its slab is already protected by the plastic case; wrap the slab itself in bubble wrap and use a snug-fitting box rather than a flat mailer, since slabs can crack if bent.
Packaging memorabilia
Signed items, jerseys, and game-used equipment need more room and more padding than a card. Use a box sized close to the item (not a huge box with loose padding), wrap the item in acid-free tissue or a soft cloth to avoid fabric snags, and pad every side with bubble wrap or foam so nothing shifts in transit. For framed items or anything with glass, use a box-in-box method: the item padded inside a smaller box, then that box padded inside a larger one. This double layer absorbs shocks that a single box can't.
Before you seal the box
Take photos of the item packed and unpacked, right before you seal it. This protects you if a damage claim ever comes up. Use enough tape that seams won't open in transit, and avoid old boxes with existing damage or weak spots. When in doubt, size up the box rather than forcing a snug fit that puts pressure on the item.