Great question. I have a few thoughts. I saw a video of a scent expert who was smelling people's breaths. I am no expert and not trained, but I know that many train by blind smelling and tasting things. You smell and taste everything on the above wheel and train your palate to smell and taste them. You can get really good. It's a focus and attention thing. I am sure there are tips on that in the bjcp or other guides. I am pretty good with wine flavors like dark cherry, chocolate, tobacco, currant, and leather. Every time I drink wine I taste for flavors and check reviews or bottle to see how right I am. I dont do that with beer. I am sure if I did I would get better. I did get better with wine over the years.
Another idea would be to taste all the beers in every style category and take notes or whatever, over and over. Maybe tasting them two to three times over a day. I am sure there are guidelines for when and how often to taste. Using palate cleansers and the like. I am from fort Collins and have been drinking craft beer since I was probably 16, graduated at 17 years old, so I know I was drinking craft my junior year. So I am close to 30 years of craft drinking at age 44. So at least I have that going for me.
I want to implore this though, the great count basie said it's either good or bad. That's how I judge beer. Good, bad, and great. Maybe some inbetween. Also, and this is a fact, like it or not, feel insulted or not, brulosophy with now well over 200 blind tests have extrapolated the data multiple times. Turns out, your average beer drinker and seasoned bjcp judge score the same. I use my wife to judge my beers, I trust her palate and opinions. It makes sense, women have better sense of smell and taste and also she hasn't chugged cigars on the golf course for 25 years. I am not saying judges aren't good at what they do or knowledgable when style is known or important. Just that when push comes to shove it's hard blind. There are numerous stories supporting this. But yeah, the real trained palate can detect in smell and taste, that entire wheel. You have some work cut out for you, but it could be fun if you love it. Examples are on that wheel for nearly every category. Overall, I could be entirely wrong and hope and expect some correction if I am. Except for the brulosophy, because that's fact.