Practice, Practice, Practice. Hunt other game not just deer helps.
I don't believe there's any question that picking up and shoulding a rifle that a person seldom touches makes buck fever much worse. On the flip side, frequent practice can have the opposite effect when nerves are calmed by something that feels much more routine. Your mind becomes less focused on the animal as a whole, but only that small target area as the mind recalls all those behaviors that make for an effective shot. You see the deer and make a decision to take it. The mind then switches focus not to the sex or size of the deer and it's antlers, but to following something that has become familiar and feels very routine.
Hog hunting and/or shooting practice during the off season from the same stand you hunt deer can be a big help in this regard. On the flip side, those who never spend time practicing at the range and never visit the lease during the off season are probably most likely to get hit with buck fever.
Perhaps not a good analogy to use, but I was fortunate to learn how to hunt from several WWII veterans who saw a lot of action in either Europe or the Pacific. These guys NEVER missed, and I'm sure it was because they had perfected the art of forgetting about what they were shooting at and focusing entirely on the shot.