Starch....I press them into submission...
I starch and press my fabric for the most part stiff...I press each seam and section as i go along...After sewing 2 swctions together I press the seam flat on both sides...then press from the top(right side) butting the seam with the side of the iron both ways. then press the paper side no steam at this point...press the seam open or to the side.. whichever way it lays flatter..then flip it over and press again..then I trim the block to the size needed...I purposely leave extra seam allowance on the section's seam this way when I press there's enough fabric to open to really flatten it..I trim it after the outside edge is trimmed..