What state/area are you hunting? If it's Colo there are only around 10 goats that have ever made B&C. If it's BC you may have a great chance of getting a booner. Are you looking for a mature billy, B&C, long hair, or nanny vs billy? Some units here in Colo the CDOW has offered so many tags that just harvesting a goat is quite an accomplishment. Obviously each unit, state, and country is a little different.
Just like any horned animal....MASS is the biggest factor in a mtn goat score. There are 8 mass measurements that make up the score and length adds only a low percentage to the total score. In Colo a 10" goat with decent mass is about as good as it gets while in BC a 10" goat w/mass may be a lot more common. You can imagine it takes pretty good optics to distinguish between a 9 1/2" monster and a smallish 8 1/2"er?
First step is trying to distinguish nannies from billies. Most guys can't tell the difference and it may take some time to figure this out. The more goats you look at the easier it will be to tell nannies from billies and a 2 1/2 year old billy from 5+ year old. Take lots of video and photos of goats and look at them in detail at home! The more time you are willing to research and scout the better prepared you will be. I've been watching and filming goats for years and there is no better place to be in the late summer/fall than the high alpine goat country!