Originally Posted by
JustAbitCrazy
Sally Collins book on Precision Machine Piecing. In it she recommends keeping the thin black line on the Omnigrid/Omnigrip rulers on top of the fabric prior to cutting, because then it gives you the space needed for the thread and turning thickness, and you don't need to try to sew a scant quarter inch seam. She also recommends starching, which has already been mentioned.
This is what a friend of mine told me to do. Sort of complicated in writing, so much easier to show in person.