I will sometimes have a devil of a time with a quilt and have come to realize that besides very accurate cutting keeping the ruler line like Maniac says above (or using my Accuquilt!), and making sure that I either use very fine thread or a scant 1/4" seam, that I MUST square up the parts of a block as I put the block together. This allows me to catch the problems as I'm putting the blocks together and either re-do or trim (if too big). When I'm lazy about this I always stuggle with block sizes being wacky. Also a beginning teacher pointed out that using steam (which I do a lot and am trying to break the habit) will cause the fabric to stretch if you are not pressing but ironing so there's distortion, or can also shrink fabric due to the moisture and heat--which makes sense since using it on a quilt with cupping problems before quilting helps tame the cupping by shrinking it. Has anyone else heard this?