Colour choices?

I have started to research into different colours, representations and contrasting, to see what will fit in my title and the overall colour scheme of my film. I wanted to look at colours that are opposite to link towards the characters.

 I have found that I want to use opposing colours, that are either really bright, or really dark, because bright and dark will show the characters appropriately but will not look professional on a trailer or a poster for the film. I like the idea of purple and yellow colours as this helps to show their characters well. I think that I will use these for my posters but dark colours as these look more professional.