These blankets are really easy to make and are so useful. They make great gifts.
I made two this time, one double-layer and one single-layer. The single layer is 20" x 36" and the double layer is 20" x 26". I think an ideal blanket is about 26" x 36".
To make the single-layer blanket, you cut the fabric, then hem it under. To make the double-layer blanket, you cut the fabric then sew it together, right sides facing, leaving a 2"-4" hole for turning on one side (tip: make it on an edge, not a corner). Then turn it right side out and iron the edges flat. Then topstitch around, closing the turning hole as you go (tip: use a wider straight stitch for topstitching- it looks nicer-- like a 3.5).
Viola! Soft and useful!