I do not starch and I do use steam when I press. I sew in opposite directions when adding strips to the strip sets. I do press in a somewhat diagonal direction. I have a line drawn on my ironing board that I set the first seam (not the edge of the first strip) on to begin pressing. I frequently sew and use full WOF strips. I recently did a bargello quilt and it turned out perfect. I did not have to change one seam. I do think you need to be careful that your machine settings are correct because this kind of quilting magnifies small tension or pressure problems. I have done this kind of sewing with my walking foot. As for pressing the seams, I follow pattern directions. I frequently divide the stip set in two pieces and label them A and B. Press the seams on A up and B down. Sub-cut alternating A and B strips and the nest and fit together perfectly.I press from the back side and then lightly press from the front side to be sure that I have not pressed in any little pleats. Then, be sure to keep strip sets square on the cutting board to sub-cut; you may need to square up slivers of strip sets from time to time to stay perfectly straight.