A grade rewards condition, and condition is mostly about storage and handling. Here's how to keep your cards mint until you're ready to grade them.
Sleeve everything
A soft penny sleeve is the first line of defence against scratches and surface wear. For anything valuable, add a semi-rigid holder or toploader so the card can't bend.
Handle by the edges
Fingerprints and oils mark surfaces, and pressure rounds corners. Hold cards by the edges, on a clean surface, and avoid sliding a card in and out of tight holders repeatedly.
Mind heat, light and damp
Direct sunlight fades cards, heat can warp them, and humidity is the enemy of surface and edges. Store cards somewhere cool, dry and out of direct light — not a loft or a damp garage.
Store upright, not stacked under weight
Keep cards upright in a box rather than under a heavy stack, which can press and bend them over time. Avoid rubber bands directly on cards.
Then grade the keepers
Once a card is graded and sealed, the slab maintains its condition for you — see what a tamper-evident slab does. Wondering which cards to seal? Read which cards are worth grading.