Making a blankie of mitered squares is Easy Peasy. Decide how big you want your squares. I chose 5" and 10".
Then, trust the gauge on the ball band and use that size needle (in this case, about 5 st/in and size 8).
Cast on 2 X the number of stitches you need (50 on the small squares (25 X 2) and 100 on the big ones). Mark the center of the row.
RS: Knit to 2 stitches before the marker, k 2 tog, slip m, k 2 tog, knit to the end
WS: knit across.
When 4 stitches remain, k 2 tog, remove marker, k 2 tog. On next row (WS) k 2 tog and fasten off.
One square made.
You'll pick up stitches along an edge to make the next square, casting on at either the beginning or the end of the row for the other half of the miter. Just keep picking up new squares as you finish each. These are pretty when planned, and (I think) almost prettier when totally unplanned.
The best part? No seaming. And if you weave in the ends as you go, when you finish the last square, you're done!
You can also make a GIGANTIC mitered square for a baby blankie (for a 40" square at 5 stitches per inch, start with 400 stitches, place the marker between stitch 200 and 201). You start with lots of stitches, but every other row is shorter than the one before.