Importance of Color
Today's digital video technology offers the opportunity for cinematographers to get highly creative with color, both on-set and in the editing suite. Use color to communicate emotion and information about the onscreen environment: light or grade a shot in hot red tones to give a sense of fiery heat, or strip all but the coolest blues and greens out of the shot to give a cold, unfriendly feeling. In between are friendlier tones: light or grade a shot in golden yellow light to give a rich sweetness to the action, or use cool deep blues to communicate the mystery and appeal of the ocean or a moonlit night.
If your protagonist is distinguished by a particular color - a red dress, say, or a cool dark suit - the colors you fill the frame with can affect how we see them within their environment. Fill the shot with objects and lighting similar to the protagonist to create a feeling of them "blending in" or being "at home" in their surroundings, or light the shot in colors opposite to the protagonist's garb to have them stand out and draw the audience's attention to them and their actions.
As with light and shadow, try to create shots with a wide range of complementary colors. Audiences are drawn into shots that offer plenty of variety, so give them a rich breadth of colors to look at without saturating your shots with so much variation that they become chaotic or messy.
If you have a lighting crew and equipment at your disposal, try to create the look you want on-set, rather than trusting the editor to "fix it in post." The better a look you are able to create on the day, the better still it can be made to look in post-production.