I did a toile in calico because I could draw and write on it. I just cut the body pieces, sleeves and a single layer for the collar and lapels. That enabled me to sort out the fitting issues. I should have actually done more fitting with the tools - I just marked a line where the back of the armhole seam needed to go but then had a marathon nightmare with the actual jacket when all the interfacing was attached, the seam lines taped and some of the lining was installed.