When using flannel, I do wash and dry to shrink it, but do not iron, as I think ironing stretches the flannel out again. I take out of the dryer and smooth any wrinkles out flat, then spray baste well so it stays in place. I do pin the corners to keep them in place. I use my IDT (walking foot and I also use a large stitch lengtht (3.0-3.5) to keep from puckering. I try to stay away from diagonal quiliting as the bias stretches quite a bit. Seems to work well for me.