Start by buying fat quarters, or 1.2 yard cuts. This way you will see your own style and choices develope in front of you. I do think that is good advice.
IF you are at a huge sale, and really love a fabric then buy 3 yards. that is 108" long and 45" wide - enough to make nice borders, and maybe even use some of the fabric in the quilt section itself. AND BUY BACKING - but only when you see the color you are always drawn to.
Remember, once that fabric is bought andpaid for, it is YOURS! So buy what you like.
Julie