I like to pick out what I call my focus fabric. This will have the most colors and the largest overall print.
I then take that bolt and hold it up to the fabrics to check out whether or not I can find other fabrics that are pleasing to my eye.
I look for at least 2 fabrics of each; light, medium and dark values.
I also try to include small, medium and larger size prints.
I stack these bolts sideways on the handle side of my cart.
I then step back and see which ones speak to me.
I also like to buy enough of one of the fabrics, usually the focus fabric to use for the backing.
I always buy extra fabric for my stash. If I have 10 or 12 different fabrics that all have harmonizing colors then I can make entirely different quilts, but have only shopped once.
I learned the hard way to never buy just 1 fabric at a time. Those pieces always seem to be my orphan fabrics.
Joyce