I use a very hot iron (cotton to linen setting) with steam, no starch. If I need it, I also have a spritzing bottle of water. While I consider preparing my fabric and pressing during the creation to be vital to my process, there are few things I hate more in life than having to iron large pieces of yardage. I'm not big on ironing at any time but piecing a quilt back is not one of my happy times.
As a prewasher, the big thing is to snatch them out of the dryer just before being dry to the bone.