I've found that using starch as you go along does help. I recently learned paper piecing and with each addition of a new piece, I paint along the the new seam and press it with my clover mini iron. then, when adding the next piece, there's no extra or folded fabric to make the new seam wonky. I mix the starch about 1/2 and 1/2 with water and keep it in a small bowl next to the mini iron and mini ironing board. i found that if i don't cover the bowl if not continually using it that the water will evaporate.