In my experience,Early on a contact grunt from a young buck works well,If he is a fighter I might try to be more aggresive.If he's walking away you got nothing to loose,whatever he hears he'll either respond or not and walk away casually.I also like to rattle early also,hit the horns lightly as if 2 young bucks were just sparring,getting the pecking order in check.That has worked real well for me.Also I like to put down buck urine and maybe make a mock scrape.Good Luck