Adjust sharpness and colors to indicate depth

By mimicking the shallow depth of field of a film camera, one can instantly give their animations the illusion of depth. By blurring the background objects and setting, you reinforce the believability of your character to the eye. Colors can also be used to indicate depth -- by using strong, saturated colors in the foreground subjects and muted, unsaturated colors in the background, sequences and character within seem more realistic to the eye.