The easiest way I found to do postage stamps is to use the grided fuseable interfacing. I use my small clover craft iron and iron them to each grid on the premarked fusable interfacing, then fold on the lines and sew the seams. Before sewing the other direction, clip the intersection 1/4"--flip the seams--one going one way and the other the opposite direction. You get perfect matching intersections 100% of the time. It takes a little wile to press them on the fusable interfacing, but the results are stunning.