I have made several QAYG, some with the backing square larger than the front (I did a tutorial on this a couple of years ago), I have done the strip/sashing method by GourmetQuilter.com, and with table runners or toppers, I have made the backing and batting the total size of the piece, and sewed the front blocks, block by block right through all layers. The sahsing can take some time, buy as previously mentioned, small whip stitches are good, or the machine sewing with Gourmet works well too.