To f/u on Bopper's comments, it is helpful to come to the BGO interview prepared to discuss your "resume." Be able to describe what you do in your key activities. If you're passionate about something, let it show.
I can't tell you how many candidates I've interviewed who are team captains or club/class officers. When I ask what they do in that role, they look at me blankly and then respond with "uh, not much" or "well, I guess I help inspire my team" or other vague comments. I try to help them with additional questions -- "Do you help raise funds? Do you recruit new members? Do you organize meetings?" Still, often time there's nothing which tells me the person is perhaps popular but isn't making the most of his/her opportunities. Conversely, I've had candidates without a lot of "leadership" on their CVs who are able to describe exactly what they do, how they contribute/improve their organization, etc.
I always give my candidate an open-ended question, "Is there anything else you'd like USNA to know about you?" or similar to ensure they get a chance to mention something if (in the rare instance) I haven't already covered it.
If you don't get this question from your BGO, you're almost certain to get "Do you have any additional questions for me?" You can use this to say, "no questions (if none), but I'd like to tell you about X, which is very important to me."
