Select raspberries and blackberries that are unblemished, dry and in an unstained container. Raspberries should be medium to bright red, depending on the variety. Blackberries should be shiny and black -- avoid those that are dull or reddish. Moisture will increase spoilage, so the berries themselves should be relatively dry. Shelf life for raspberries and blackberries is short, and they should be consumed within two to three days of purchase. Eat at room temperature for fullest flavor.