It is tough to rough score a deer in the field. It takes a lot of practice and time to do it half-way consistant. I have been working on it the last 5 years or so and I am still not real consistant at it. When I watch hunting videos, I am always trying to guess the score before they show the score on the screen. The main thing, 1st off, is to know your scoring chart, you have to know how to score a deer before you can accurately do it in the field. Go to the Boone & Crocket website and get the score sheet printed out and take some racks you have and start scoring them. Once you get that down then you can start measuring the deer in your head. After a while you can just look at the deer and get a general idea of what he will score. I have improved a lot since I have started, but like I said it takes a lot of time and experience to get only half-way consistant, and some people do it better than others. Hope I helped you out a little, and good luck on your hunt.