Out of a collection I buy what catches my eye the most, usually the prints.
I can always fill in the prints with tone on tones, water colors, batiks or other subtle fabrics that read as solids. There are so many of these from lights to darks, it is usually easy to get enough to fill in and compliment the printed fabrics.
Solids are also readily available and work well with all styles of prints.
Keep an eye out for scale too, large, medium and small prints. They all have their places in quilt patterns :D:D:D
Some patterns have mostly lights/mediums with a few darks that pop. Others are the opposite. Some may be mainly mediums with a few lights and darks thrown in.
It can be up to the quilter too... changing the colors scheme to suit his/her tastes :D:D:D