Mine was very simple.
He went through the standard list first, asking about acedmics, my grades, I showed him my transcript, asked him about sports.
Other questions he asked were :
Why do you want to participate in ROTC?
Why didn't you apply to the USMA? (He was graduated from there)
What was your most difficult experience?
What branch do you want to pursue?
What distinguishes you from other applicants that I can tell the board? (I said my serious tone, integrity etc and gave a couple examples)
Then at the end he asked me if I had any questions. I saw he had the Ranger tab, I asked him about his experience in Ranger School, and that got us in like a 20 minute conversation).
Be serious, proffessional, give a good handshake, speak with a loud clear voice, look him in the eyes, be honest, sit up straight and don't stutter like a madman (I saw the scoring papers, part of the points are for composure, tone, etc) Also, come in with a fresh cut, cut fingernails, shave, brush teeth (lol), and I dressed in khakis, and shirt and tie.
Also, let him know your human, and not a robot regurgitating answers.
All in all, my interview went well besides that question on why I want to purse military intellegence. ROFL, there was about 2 minutes of silence me trying to form a coherent answer, and when I spoke, a bunch of crap came out. BUT, I eventually gave a well formulated response which he liked. He told me that I was "a fine young man" and to email him personally on how I do.