RE: Tricks that you use when field judging whitetails?
I am a math minor and there is no way I am doing any addition in my head with a bow in my hand. I look for the pot-belly, roman nose, massive frame (and sometimes but not always, neck) and swaggering walk of a older buck. As for antlers, I can generally judge the 10" range a deer will fall in if I have a few seconds to look at it. I put deer into +/- 5" ranges in my head and it works for me. I have measured quite a few deer and seen more - to me it is just building on memory.
The one trick that was already mentioned on here is to look at how far the beams come out(and wrap around) in reference to the nose.