Colour was one of my favourite subjects. We were having planty of experiences with painting and used various techniques.
This is a picture where my task was to change athmosphere. There was a cheesy photograph about hungarian parliament at sunset, and this is how I changes it.
Though the picture is 180 degrees turn compared to the original, I was glad to practice how to paint water and air.
The picture above is a sketch about usage of cold and warm colours. Though it is not representing clearly the effect, they say that cold colours in the back of a picture (blue) and warm colours (red, orange) at the front can approve spatial effect.
By the way, colour is a very complex physical appearance that has been studied by Isaac Newton, Goethe and many other famous physicians and artists. There is so many aspects I can only advise to sit down and think about it for a second.
Complimentary colours are existing, but why to see so scientifically if it is enough to enjoy the effects. Johannes Itten wrote very nice studies about colour.
red and green are a pair for example. just like violet and yellow, or orange and blue.