One of the most beautiful bind off techniques is the I-cord bind off. It makes a lovey round edge that is completely finished. It is perfect for hat bind-offs; make a swatch and give it a try!
With 2 dpns, cast on 4 sts. K3, then, with the RS facing, K the last st tog with the first st on your garment. DO NOT TURN WORK! Slide sts to the right end of your needle to work the next row. K3, K the last st tog with the next st on your garment. Repeat until all sts are bound off, the bind of your I-cord sts and finish.