The Boone and Crockett Club’s Field Guide to Measuring and Judging Big Game is a solid reference book, one I refer to a lot.
It has good tips and advice for: 1) how to field-judge a buck better than you ever have on the hoof; and 2) how to rough score that rack reliably once you’ve shot a deer dead and have him back at the house.
There’s info not only for whitetails and mule deer, but also for antelope, caribou, elk, bears…any big game animal you hunt. There’s even a chapter on judging and scoring a walrus skull if you ever do that :)
At $25, a bargain for your bookshelf.