I'll be honest - I didn't really plan the composition. I just started brushing on paint. Not exactly a masterpiece, but the black circle does dominate.
For the second composition, I created a light glaze by mixing the red paint with gloss medium. I wanted just a sheer layer of color over the black circle. I thought the shine of the glaze would make the circle less dominant. Then I added a black vertical line (using matte medium with the black, so it stands out from the glossy red finish). The glaze over the black circle was too sheer, so I went over it again, but that ended up too thick. It really obscures the black circle - I think that's probably cheating. Good thing it's not for a grade!