Feces identification, also known as scat, can be a difficult task as feces change according to the animal's diet. However, by asking the right questions you can go a long way to reduce the number of available suspects.
Be safe. Droppings are dirty and germy. Avoid handling droppings without proper protection, which includes avoiding inhaling around it. Some diseases may contracted through dust borne particles.
Are the ends flat or pointed or is one end flat and the other pointed?
Is it smooth from one end to the other? Or is it segmented like a natural fibered rope?
Is there one dropping or multiple?
Can you identify any hair or food particles in the droppings? Sometimes corn, berries, seeds, and insect wings aren't completely digested.
What time of day do you find the droppings? Would they have been left at night or during the day?
Is it a one time event or does it occur in the same general spot for several days?
What state are you from and what type of habitat do you reside in (ie. woods, urban, suburban, agricultural etc.) as this helps us know what types of animals live in your area.