What is the best way to store seeds?

Seeds should always be kept dry, cool (close to 4º C if possible) and away from light.

The no-frost refrigerators are a good place to store seeds, preferably inside a film canister or vacuum-sealed in a plastic bag, to avoid moisture condensation.

In the absence of a fridge, seeds will stay viable at room temperature for 6 months to 1 year, sometimes more.
Try to avoid exposure to moisture, temperature changes or light.