Decide on a creature to make. To keep it simple, choose a well-known image that you can piece together in your head, such as a sheep, dog, fish, cow, penguin, cat, pig, etc.. Once you have the image visualized, start to mentally separate the different sizes of objects needed for its parts. For example, a sheep will need one big part (body), one small part (head), and four small stick parts (legs).
Match food items to the proper sized parts that you need, and then filter for shape. Sculpted food creatures can either be carved with tools or simply pieced together. If carving, virtually any item that can be carved, such as a turnip, eggplant or squash, can be used. If you are relying on the natural shape of the object, visualize which fruit or vegetable would suit each part the closest. Sheep are oval and woolly, cauliflower is the best fit. Sheep heads are black and oval, perhaps a black olive. Penguins are smooth and cylindrical, similar in shape to a small eggplant.
Use any edible item to add limbs or appendages to your creature, including dried spices (like cinnamon stick arms or clove eyes), nuts and even pickled items. For small things such as ears, flat wings and fins, flaps carved into the body work great rather than adding a separate object.
Construct the creature once you have it envisioned in your mind with its various fruit/vegetable parts. You can piece together the items (such as placing the head on the body) using either toothpicks or glue. If you prefer everything in the sculpture to be edible, use edible pastry glue found at most baking supply stores. Be creative, and don't forget that you are making art, and no one can tell you how to make art.