Let It Breathe
In order to do their work, microorganisms need to breathe. Turning your compost often will ensure the proper aeration. If your pile is large, turn it a section at a time. Stirring it up not only gives your compost a shot of fresh air, but also distributes excess water and speeds up the decomposition process by promoting contact between the greens and browns. Compacted piles also have a tendency to smell. A few turns can reduce the odors.
You'll want to mix and fluff the compost. With a long-handled rake, pitchfork or even a long stick, move the inside of the pile outward and the outer areas to the inside. It's best to do this every two to four weeks [source: The City of New York].