you come across a large amount of droppings in one area, you can be pretty confident that you are very close to a major feeding area. Look around and get a good idea of what they are eating and where the best place may be to setup. Below is a picture of some old droppings. Notice the grey appearance. Newer droppings will be much darker and have an unmistakble odor that can be smelled by a hunter from a good distance.
also notice the black muck color on the vegetation