knowing not only how to use cow sounds and bull sounds but knowing when to use them is what matters imho. i'm still trying to learn all the different elk talk and when to make certain sounds myself. sometimes i confuse myself timing is everything as i'm finding out. make the wrong sound at the wrong time and the gig is up and you just ran him off. i think #1 is learning how to use a mouth reed just because of the versatility a diaphragm brings to the table. i have ElkNut's dvd's and PlayBook that go in depth and i have killed several cows and a spike using his techniques. now granted i was trying to kill big bulls at the time but i am an equal opportunity bowkiller and when i have had golden opportunities to kill cows i've taken them. not bad for 4 years of hunting elk with a bow so far.