I was inspired by an artist's work, I forgot his name, but he worked on the shrek movies. I didn't copy his color scheme, but I tried to implement the way in which he selected colors and also the graphic style of painting them.
It took a lot of fiddling. I knew I wanted to have very vibrant colors like oranges and yellows to draw attention and have greens and blues to act as shadowed areas. But the implementation of that logic was just a whole lot of fiddling.