Think About a World Without Color
Oh for the days of black and white film. Well, even with digital color sensors you can still see in black and white (sort of). A good way to think about the use of color in your photographs is to think about the world without color.
Try removing most of the color from your image, not in “Photoshop” but on location. A gray, foggy day will give you the sense of being without much color, as will some subjects like a subway station or a white tiled bathroom.
Try looking and finding how much is out in the world that is predominately black, white & gray.
Then try adding one primary color to you images. Shoot for a set time period looking for black, white, gray and then add either red, green or blue. These three are the primary additive colors from which all other colors are made. If you can learn to see them you can learn to use them in your compositions.