Count me in the group that chooses a print fabric I really like then picks my other colors and fabric prints to go with that first (the focus) fabric.
That focus fabric can then become the star of your quilt or you can move it into the background and use your other fabrics as the stars. Spread it out and lay your fabrics on top of it, do they show up well and make the eye stop on them? Or does the first fabric call your eye away so that you feel compelled to look at it? If the second thing happens, then you would want to use that fabric as the star of your quilt. Make it the center or main fabric in the blocks, and use the other fabrics for accent. If you don't want to use it as the star, then just keep the other fabrics and you don't have to buy that focus fabric. Look for a fabric that you can lay your other fabrics on that seems to "hug" them but lets them draw your eye first. That will be your background fabric. Often this is a solid or tone on tone. I am partial to tone on tones for variety but am not against a good solid when the main body of the quilt is very busy.