When I sew two pieces of fabric together...right sides together I always "set" the seam by pressing the seam with my thumb and moving it along the seam with pressure applied, first. I then turn the fabric making sure the seam is laying in the direction I want it to go (toward the dark fabric) and finger press it really well. Sorry I don't like to press with an iron until I am ready to sandwich it.....I am a finger presser.