Lots of threads at least on blue & gold USNA interviews, search for them.
Dress and look professional. Look and act like you want to be an officer.
Know why you want to be a naval officer.
Know the different Navy communities and be able to articulate which community you want and why.
Know your resume. Know examples of how you have shown leadership.
Know examples of when you have spoken to a large group.
The Navy is looking for STEM type applicants. Be able to articulate your involvement in math, computers, and science both in and out of the classroom.
What can you add that they don't already know about your physical fitness or physical activities.
Are there any special circumstances that they should know about or that you want to highlight
I have seen these categories and what would give max scores.
NROTC Program Motivation: Applied to all programs but definitely wants Navy and NROTC is first choice.
Service Over Self: Explicit in service over self - just wants to serve - May have other desires but overall, amenable to other communities - Fully career invested.
Physical Fitness: Exceptionally fit - Top athletic condition - Superb muscle tone - Embraces a culture of fitness - Muscular, fit and trim
Appearance/Bearing: Superb - Very mature - Dressed to impress - Sat up straight and was attentive during meeting - Conveyed great respect - Meets Navy standards of appearance already
Communications: Exceptional - Thoughtful and clean in response - Articulated answers with ease - Maintained eye contact throughout - Conveys professionalism and confidence
Overall Suitability for NROTC Program - Great potential to excel as a midshipman/officer - Highest recommendation - Of all applicants interviewed - Top 20%
Most importantly, be yourself.
After your interview, post back and let us know what you learnt.