Here are eight movie stills from very popular blockbusters, so that you can get an idea of how color grading is used to help tell a story.
The most popular effect among action movies is the Teal-Orange look:
The Teal-Orange color combination can also found in scenes where there are no actors.
The Transformers movie is one of the films that I believe over-does the Teal-Orange effect.
But that is not the only look. Movies like The Matrix use green instead of blue, because it helps push its story forward.
The movie Amelie uses a different complimentary color combination, the Red-Green combination.
Post-apocalyptic movies like Terminator Salvation use a desaturated gloomy look.
There is no right or wrong way to color grade an image (or movie). It is all up to you, the artist, and the story you are trying to convey.