I suggest you find some patterns you like and buy yardage for them. After you make a few quilts you will have leftovers that will start building your stash. And after you make a few, you will get a feel for the kind/style of quilts you like to make. I make mostly modern quilts which tend to take fewer fabrics but larger quantity of each and lots of solids. If you like scrappy, look for bundles of "destash" fabrics on eBay or etsy to build up a variety of smaller cuts. If I see a fabric line I love without a pattern in mind I buy 2 yards of each fabric. When I started out I bought 1/2 to 1 yard and that often is not enough now for the quilt style I like to make. I also advise against buying just to build a stash as I did some of that at the beginning too and still have most of it because They don't coordinate well together and aren't in the right quantity. I will eventually use them in scrappy or string quilts however. Just buy for each project and you will be surprised how fast your stash will grow!