Notes from Knitting-and.com about yarn, needles, and gauge:

Materials:
Straight needles plus at least one double-point needle in similar size;
baby (or other) yarn (see gauge note below)

Gauge:
After they’ve been washed a few times, 8 stitches to the inch. I’ve made the same pattern in bigger yarn on bigger needles and gotten slippers for the whole family, so I suggest using whatever yarn you have at the appropriate tension for it.