I had a sister whom was educated in her field of art, she suggested that if you look outside you will see lots of colors and it depends on the density of the color which you could consider a neutral color, and yes, even red. She also helped me when I was first quilting and putting colors together, to always use uneven numbers, such as 3, 5, 7, etc., in choosing my colors and to vary the depth of the shades I chose.