Sweet potatoes fall into two categories: moist and dry. The skin of the dry type is usually yellowish tan or brown. Its cream-colored to yellow meat is dry and crumbly after being cooked, much like a white baking potato, and its flavor is not sweet. The skin color of most moist types ranges from copper to dark orange. This type's sweet, bright orange flesh cooks to a much moister texture. The moist sweet potato often is erroneously labeled a yam in many supermarkets.
Look for small to medium, smooth-skinned potatoes that are firm and free of soft spots and blemishes.
Sweet potatoes are not good keepers. Store them in a cool, dry, dark place for up to 1 week.