A blind hem stitch is the least visible stitch on the outside. Hand basting the hem in place leads to the best results.
Fold the hem over twice, then pin it in place.
Baste the hem in place.
Remove the pins.
To hide the knot in the thread, sew the initial stitch through the hem only.
Sew a small stitch through the front of the fabric, then continue the stitch through the top of the hem. Make sure the thread loops underneath the point of the needle.
Continue these stitches across the hem, then remove the basting.