When I start a new quilt or change machines, I run the 1/4" test: sew three 1.5" or 2.5" strips of the fabric together. Then measure to insure that the middle strip measures either 1" or 2" and that the block is 3.5" or 6.5" wide. This is necessary because the thickness of the fabric and the thread may vary depending on the materials you're using. It took me a few times of making unequal blocks and ripping out before I realized that the 1/4" mark is not always in the same place. So I think I've got this skill working for me, but I'm still not as accurate with my cutting as I need to be. I try so hard and think I've got it licked, then I'm off just a smidgen. Good luck with you progress.