If you don't sort your scraps by color and it feels like too much work to do start that's fine. All you really need is to pull out the color you have the most of to make it your background fabric. The center of your blocks can be totally scrappy and mismatched as long as they contrast well enough with your background. Example: there wouldn't be much contrast if your background was navy blue and your scrappy centers had navy blue and some other colors in them. However, if your centers were mixed light colors, yellows, pinks, etc there would be enough contrast to make your scraps pop. You can also do the opposite - make your background totally scrappy and use low-volume fabrics for the plus center or 'cross blocks' - like the example below.