Sharon Schamber uses Faultless Heavy spray starch. Spray on one side, turn fabric over and iron with a hot dry iron. Spray turn fabric over and iron. Spray, turn fabric over and iron. So 3 times total. Ironing from the other side will force the starch into the fabric and you won't get flakes.
Also to clean your iron either hot or cold, she says to dampen a Mr. Clean Magic Eraser sponge, place on a towel on your ironing board and drag the iron across the sponge. The gunk will come off rather easily. In her tute, it looked like it worked better with the iron being cold. I was amazed at that, but have used the Magic Eraser on other things and been amazed at how well it cleans things.