Unify your colours
No matter what medium you’re using, it’s a good idea to make sure that your artwork has unifying colours. This consists of a particular colour palette, mood and a way of spreading these across the entire art piece. Unifying your colours brings harmony and cohesiveness to the piece as well. You can also achieve this by using a tinted paper, or painting the background before starting your work. This will show through whatever you lay down on top of it, thus giving it an appearance of cohesion. When I use coloured pencils, I’m fond of using tinted paper produced by Kraft.