There are more shades of white paint than there are of any other color. Ethel Rompilla, who has been teaching students about color theory at the New York School of Interior Design for 16 years, offers some advice.

Although every rule has its exception, rooms facing north, and therefore away from direct sunlight, generally look better with warmer tones (whites with undertones of yellow, cream, peach, pink, or tan), while rooms that face south, which have natural sunlight, should have cool tones (whites with hints of blue, green, gray, or violet). Below, see just a few shades from Behr paints.

The best way to compare whites is against a stark white.

Rather than paint a swatch on the wall, take a two-by-three-foot poster board and paint it. Move it around the room to see the way it looks at different times of the day and with different pieces of furniture. The intensity of the undertones will fluctuate with the changing light.

Be careful of stark white walls. The result could be glaring, especially if a room gets a lot of light. "It's like being snowblinded," Rompilla says.