To match points perfectly, take a pin and push it from the wrong side to the right side vertically at the very tip of the point. Now push through the very tip of the point to match it to. Be sure to keep the pin vertical. I put two fingers on the underside, one on each side of the pin and hold it vertical, as I place a pin on each side the hold the fabric in place. When you stitch, your thread should be just a thread towards the edge away from the points to allow for the fold when opened.