The best way is at room temperature, but not in direct sunlight and away from any heat source. If you're planning on eating your fruit in a few days, store them in the refrigerator, but note that it can make the skin tough or rubbery. Also, avoid stacking the whole oranges on top of each other in a fruit bowl which can quickly cause bruising, spoilage and mold growth. Lightweight mesh bags are a great way to store them until they're ready to enjoy.