The gap between a near mint card and a lightly played one is real money, and it is usually lost in ordinary handling rather than in dramatic accidents. The habits that prevent it cost very little.

The basic stack

• Penny sleeve. A thin, cheap sleeve, straight onto the card. This alone prevents most surface scratching and costs almost nothing.
• Toploader or semi-rigid holder. A hard shell over the sleeved card, which stops bending and corner damage. The standard way to store or ship anything valuable.
• Team bag. A resealable outer sleeve around the toploader, keeping dust and moisture out and stopping the card sliding free.

For a card you play with rather than store, a single quality sleeve is the right answer. Double-sleeve anything expensive, with an inner sleeve going in the opposite direction to seal the card.

Storage

• Upright, not stacked. Weight on a stack over months causes bending.
• Stable temperature, low humidity. Humidity curls foils and can warp cardstock. Lofts and garages are the usual culprits.
• Out of sunlight. Direct light fades card faces, and the damage is permanent.
• Binders with side-loading pockets for anything you flip through. Top-loading pockets let cards fall out when the binder is turned over.

Shipping

Most damage happens in transit, and most of it is preventable. Sleeve the card, put it in a toploader, tape the toploader closed, never the card or sleeve itself, and sandwich the whole thing between rigid card in a bubble mailer. For anything genuinely valuable, use a tracked and insured service, and photograph the card and the packed parcel before it goes.

Proportion

This is worth keeping in perspective. The catalog is overwhelmingly cheap cards, commons and uncommons worth pennies, and elaborate protection for those is wasted effort and money. Sort once: the handful of cards worth real money get the full treatment, and the rest go in a bulk box.