If only one light in the center of the ceiling, add additional lighting in a couple of corners. Dark corners makes a room appear smaller.

Heavy drapes and blinds may block or reduce lighting. Change these out with stylish lighter drapes or blinds.

Too wide or narrow
Illuminating the longer walls more than the shorter ones will draw attention to the longer ones. This resizes the room, so that the eye is not concentrating on the short ends. Large art pieces or large pictures, should again be on the longer walls, because you do not want to draw attention to to the short ends.

Ceiling looks too high
Use fixtures that direct light downward. If light shines upward where it illuminates the ceiling it will draw attention to the high ceiling. Floor lamps with shades that are open at the top allowing light to shine upward should be avoided.

Wall sconces directed downward are another type of lighting that will help take attention off of high ceilings and make the room appear more proportionally.