Fun quilt. I too would stitch in the ditch around the blocks to secure and cross hatch in the blocks. If you have a walking foot, it may have a guide on it which can be used to measure the width of a line. Then I would draw a diagonal line through the center of each block in both directions. Stitch on the line, then for the next line, use the guide. The quilting part always intimidates me, but this method works for me. I bought a foot for the stitch in the ditch and it really helps.