Monochromatic is using a single colour that permeates through your film. Analogous, a colour scheme of three colours next to each other that creates harmony. Complementary, two colours opposite each other, often used for contrasts. Triadic is three colours evenly spaced out on the colour wheel, and tetradic four colours evenly spaced out. Both of these are less common and can add a cartoonish element. Adding any more colours and it becomes challenging to balance your colour scheme.