I tend to find one "focus" fabric that really talks to my soul. From there I start building to see which other fabrics care to play with me. I normally for me use from four to seven fabrics in a quilt depending on the focus fabric and what my spirit leads me to create. I would invest in the makings of a design wall or folding screen that you can use to audition your combinations on from your stash. At the quilt shop I tend to find a corner with great lighting that I can use for several minutes to pull various bolts together and stand away from to read the complete picture. I also invite other opinions, but in the end the combination is my decision.