I've found the most natural method to be one that counts to 20 taught to me by my friend Romie. Instead of counting fingers or memorizing hand positions you count the joints and tips in your five fingers. Each finger has four, so you can count to 5 × 4 = 20 on one hand.
For 1 through 16, point at the joint or tip with the thumb of the same hand. For 17-20 use the middle or index finger, whichever comes up more naturally. For 17, you're really just pointing at the pad of your hand — it's too hard to feel the joint under there.
Try this at home! It's nice to be able to count so high on one hand and it's less cumbersome than more exotic methods. Of course there's nothing to stop you counting 20s on your left hand and units on your right, allowing you to count to 20 × 20 = 400 on two hands.
St. Nicholas counts to 8