Use nice, bright colors and a size J hook. 4 ply worsted works best and you will need about 40 oz or so and use double strands throughout or use a strand of worsted weight with a strand of washable sock yarn or baby yarn. It's just a toasty warm lapghan.
Each row is done in sc with a ch 2 at the end. Turn and sc down next row starting in the st closest to the turning chain. Continue till lapghan is 40" long or desired length. You can also sc in the back loops only to add a ridge along every other row.
This works well for a baby afghan too.
you are a more experienced crocheter you can sure spice this lapghan up
a bit by varying stitches. You could skip every other stitch, and
substitute a chain 1. Then do several rows in sc, and once again
skip every other stitch. Maybe do every other row in double
crochet with ch 3 at the ends. Be creative! If you do
to do all single crochet, it will form a material that you could cross
stitch on too!