I've killed a decent amount of deer including some fairly big bucks. Like MeanV said, experience is the best teacher. What works best for you?
This is what I do for any animal that I hunt.
Once I spot an animal, I try to determine if it is one that I want to shoot. When I decide that I want to shoot, I switch all focus to a spot I want my arrow to hit and how I'm going to get it there. No more looking at the antlers (worst thing you could do), just the spot, where the animal is traveling and how I'm going to get the arrow off, quietly and Score!
This works best if you really study deer/animal anatomy along with pics of different shot angles. That spot that I pick has to make for a quick clean kill. After that it is all experience.