Circulate air in the normal counterclockwise direction in the summer so that the air moves downward from the ceiling. The moving air will make the room feel cooler.
Set the ceiling fan to run clockwise, or in reverse, in the winter, to move the air that's been warmed by your home's heating system around the room. Since heat rises, the warmest air will rise to the ceiling and stay there unless it's circulated.
Run your ceiling fan on the low setting most of the time, regardless of whether it's moving counterclockwise or clockwise. If your fan hangs more than 10 feet above the floor, however, it will need to be set to the medium setting most of the time in order to provide good circulation. The high setting can be used for more of a breeze in hot weather, if desired.
Use ceiling fans in several rooms at once to keep the air circulating throughout the house.