There are number of things you should be aware of in terms of color relationships. If you scan a print image, the system must translate the colors from a subtractive to an additive mode. This means the colors of the scanned image displayed on the screen may not match the original colors of the image. There is software to help solve this problem, but spend too much time worrying about the technical terminology, just remember to be prepared for some discrepancy in translation. You must also consider how a color will work in terms of its background and neighboring colors.
Spectral neighbors are hues that are next to each other within the color spectrum.
Blue and green, red and orange, and yellow and green all neighbor one another on this continuum. Use these pairs to suggest shadowing or dimension. However, avoid these pairs when you need distinct visual boundaries because the contrast between them is low. These pairs are more useful to draw out subtle relationships. If you put them right next to each other they may appear to move or vibrate.