I started just picking out fabric as I go; FQ that I really like or a yd of this or that. Last yr a lady posted on CL that she had some quilting fabric to get rid of so I jumped at the chance. I still have to go thru the box and already know that it all isn't quilting fabric but some is really nice. What I don't use for quilting/sewing will go to thrift store.
Another time a lady wanted someone to make "quilts" for her in exchange for fabric. They were more like double layered recieving blankets. I got some really nice fabric from her. So mine is a collection of lots of FQ, etc that just happened to catch my eye and some leftover from projects. When I started taking Civil War classes I went all over collecting it because I didn't always want what was in my kit each month so I have quite a bit of that but that too is mostly FQ. A little of this and a little of that makes my sewing room look like I have a lot to anyone who doesn't really sew.