I have met very few guys that moved into killer mode easily, that truly loved the sport. Note I said "easily", let me explain:
I think new bowhunters should shoot deer. Period. Not wait for trophies, not try and estimate P&Y scores from the tree. Shoot deer. Get some success under your belt.
When I was in my teens and twenties, I would get rattled when any deer came within shooting range. Slipping my brain into the predator gear was damned near impossible. Gradually it changed. I suppose my brain started to realize "we have done this before" and things started to come together. Today, if I decide to shoot, my attitude changes, things slow down, my focus comes together, and I do ok.
Now....I have met several guys along the way, guys getting started in hunting later in life, he seem to have NO jitters. I believe that they have no concept of hunting's history, drama, etc. rattling around in thier head. Nothing gets in the way with "see deer, shoot deer".
I think working through the jitters, buck fever, whatever, is one of the rewards of being a true sportsman.
P.S....I have a whole different theory for guys raised on a farm, where killing an animal is as mundane as cutting the grass...I have never seen a true farm boy nervous about killing a deer.