Install a ceiling fan. Ceiling fans come in a wide variety of styles and many have light fixtures attached, giving you additional lighting. Ceiling fans also come with a toggle switch allowing the fan to turn clockwise or counterclockwise. This allows you to pull the warm air from the ceiling in the winter and allows for greater cooling in the summer. The fan should rotate clockwise for maximum cooling in summer and counterclockwise for drawing the warm air downward in winter.
Clean the air ducts. In homes with central heating and air conditioning, bedrooms have vents to allow the warm or cool air into the room. Keeping these vents clean will allow for the best air circulation possible.
Open your windows. On nice days where the outdoor temperature is mild, open your windows to allow the old and stale air to be replaced with fresh air. Turning on a ceiling fan while the windows are open will improve the circulation of fresh air into the room. While in the case of circulation of the air the rotation direction doesn't matter, if you also want cooling effects make certain that the fan is rotating clockwise.
Use a portable fan. If you're renting or simply don't want to install a ceiling fan, a portable fan may suit your purposes. When placed in an open window a portable fan can also draw in fresh air from the outside more efficiently than a ceiling fan.