You should store the ground coffee in an airtight container to prevent it from the exposure of light and moisture. The best way to store the coffee is by using a ceramic or metal container and it's important to keep the containers in a dry and cool place. Visit http://www.wisegeek.com/how-should-i-store-coffee.htm for more details.
Not freezer!! It kills the flavor and aroma. In an airtight ceramic or glass container at room temperature. But the best way to have the best tasting coffee is to ground the beans just before you make the coffee. keep those in an air tight container.