I agree with the others' comments about taking time to pin accurately. The first quilt I made though, some of the seams didn't line up AT ALL, despite squaring and trying to pin accurately. Baffled both me and quilt group tutor until I realised what I thought was a 1/4" foot wasn't QUITE 1/4" (cheap machine that a neighbour was getting rid of). The pattern measurements had obviously been calculated to account for seam allowance, so that the pieced blocks would end up the same size as the single fabric blocks, but because of the inaccurate foot, they didn't, so the rows didn't match properly.