The simple thumb rule is to look at a color wheel. Colors lying next to one another will create a harmonious look in the room whereas those lying on opposite sides will create contrasts.

So you need to decide if you want to create a harmonious look, go with shades of mauve. And if you want to create a string contrast, go with shades of oranges. Typically peach or light orange will go with well with sky blue.

White, of course, is the safest bet. Hope that helps...