When I was a newbie I would pick out the pattern before the fabric. I didn't want to build a stash so I only got enough fabric to complete each project. Now it can go either way since I do stash a little. Usually its pattern before fabric, but I've had a couple times where the fabric had dictated the pattern. Sometimes I'll have an idea like "I want to create something with a lot of blue in it" or "I want a lot of Asian prints", but not know what kind of quilt it will turn into. I had green strips that were left over pieces from a quilt and they were going to border that quilt, but I never finished the quilt and one day while organizing the stash I happened to lay some pink batiks I had near the strips...now I'm collecting pink fabrics to one day make a green and pink Railroad quilt. So it can go either way, but I would say the majority of my ideas have been pattern first then fabrics.