I mainly buy fat quarters cause I have found I like lots of different fabrics in my quilts & you need so little if you use lots of different ones. I also buy half yds, or bigger, if on sale, or good priced, to use along with them. I used to sew alot of my clothes, mostly tops, so had alot of stash from that when I started, & still do. Buy what you like, or appeals to you, or, if it's different, what looks good together. Then you will have more that goes with it in your stash, & you will enjoy working with it more. It's alot more fun & interesting, if you are working with prints/fabrics that appeal to you at the same time!... Just keep buying a little here & there, as you can afford it, & it will start adding up (multiplying) before you know it!