Before sewing on my binding, I usually trim my quilt to straighten the edges and square up the corners. Most of the time the quilt edge is straight, but sometimes it has gotten crooked a little bit during the quilting. This way I know that my quilt edge is straight and corners are square. After sewing on the binding with a 1/4" seam I add a 1/2" strip of batting inside the binding so I know it is full. It just looks nicer than a flat binding.