Measure each square as it comes in. Usually, if it's within "a hair" of 12" either way, I let it slide. If it's more than a half-inch too small, I add to it with white or a color that matches the square, but not the same yarn I'm going to use for assembling.

Assuming it's a 12" square, I take my assembly yarn color and make 27 sc (single) along each side, plus 3 sc in each corner. If the original square actually has 30- or 40-some-odd stitches, I will decrease as needed. For example, 2sc, 1 dec, 2sc, 1 dec, etc.

For round two, in the first corner I will do 3dc, ch1, 3dc. Then skip two stitches, 3 dc in the next stitch; skip two stitches, 3 dc in the next stitch, etc. So there will be 9 "granny" clusters on each side, plus the 3dc, ch1, 3dc in each corner.

To join, take two squares wrong sides together, join the corners with a slip stitch; ch 3; sc in the next big space, ch 3; sc in the next big space, etc. At the end of the square, sc in both corners together (not in each one), ch 2; pick up two more squares and sc in the corners, repeating the (sc, ch 3) across the square.

Join the 'rows' of squares together, then crochet the 'columns' of squares in the same way (sc, ch 3, sc).

Then I go around the whole afghan with a dc or hdc, making sure to decrease in those 'corner' spots where two squares have been joined together. The final round is a shell pattern of 7dc in the corner, skip one stitch, sc, skip one stitch, 5 dc in next stitch; etc.