Place the Potatoes in a cardboard box, paper bag, mesh bag or basket to ensure good ventilation. Plastic bags won't allow them to breathe, and will shorten their shelf life considerably. Store it in a cool, humid and dark place at an ideal 45-50° temperature range. Avoid putting them in the fridge as the too cold temperature will turn the potato starch into sugar.
Store Red Onions in a dark, cool, dry location in the kitchen. Avoid placing them in a plastic or covered container as it needs to breathe. After days of storage, always check for any spoiled, moldy bulbs and discard at once to avoid affecting the others. Any sprouting bulbs must be used immediately. You can also store it in the fridge but take care not to place it beside other food and produce which can absorb the onion's odor.