I usually buy at least 1 yard, sometimes 2-3 yards. However if you make mainly scrappy quilts, you could probably get by with 1/2 yard cuts. Since I usually make more modern designs, they usually use fewer fabrics in number, but require larger yardages. Also, if a fabric is the 'focus' fabric of a planned quilt, I will buy more of it (2-3 yards) and smaller cuts of the coordinating ones. But I also want to have enough for the binding, so don't forget that. If it is a fabric you can use for a backing, get 6-9 yards if it is a really good deal.