All about learning how to adjust for wind (left or right). You never have to adjust vertically as you always want to release perfectly level with the bullseye. Once you figure the wind just keep an eye on it every shot and practice away! One more tip - take your shots quickly (within 3 seconds) as the target begins to shrink the longer you wait. This makes it much more difficult.
For me, this was the most fun to achieve thus far in this game as I really felt myself get nervous and tense up the closer to perfect I got. (you have to shoot 12 perfect arrows in a row to win the thing)