Feng Shui recommends that a pair of curtains or drapes is more beneficial in making the best vibrations circulate inside the room.
The color of the curtains depends upon the direction, which they face, for example, the ruling element of the western direction as per Feng Shui is metal, and hence white or grey colored curtains are more suitable for the doors and windows of a room facing the western direction.
The same way the ruling element of the Northern direction is water, hence the color blue or different shades of blue, which symbolizes water is more suitable for a room facing the North.
The South symbolizes the fire element, so red, bright or flaming yellow, orange, pink, purple, and other colors symbolizing fire are considered to be lucky.
The East represents the wood element and so the color brown and green are more suitable for the curtains or drapes of a room facing the East.
The Feng Shui recommendation are based upon the directions, the Tatva and the color which it represents, so if you believe in Feng Shui, make the most out of the recommendations, otherwise forget it.