I really liked the block we made for April's Promise Circle of do Good Stitches and I think I've finally figured out how to get my blocks to come out 12.5" or more square. Pressing the seams open and doing an even scanter 1/4" than I was doing previously really helped. Also I've started using a shorter stitch length which has helped with the edges from unraveling....of course when I have to rip out my stitches it is a bit of a pain...win a little, lose a little. In the end it all came out good.
The tutorial for this block can be found on Fresh Lemon Quilts site.