Are you already at USNA? And aspiring to SWO(N)? Or will be attending in this incoming Class of 2027?
Doesn’t matter. You work hard at all your academics and leadership courses at USNA, staying sat in all graded areas. First hurdle is graduating USNA and being designated SWO(N). Becoming proficient at effective study habits and mastering time management and prioritization of competing tasks will be critical.
An engineering degree makes the most sense, but other majors go nuke paths as well, including English, History, etc., as long as they do well in STEM courses and take any additional recommended courses, sometimes giving up summer leave blocks to attend voluntary summer school.
If you are headed to USNA, you will get briefs on all kinds of things, have an academic advisor, talk to upperclass going that path, encounter staff officers from the nuke communities.
Next hurdle is going to your ship and being a good JO, working hard at earning your SWO qualification and learning how to be a good leader for your sailors. If you don’t do that, you are DIW. Dead in the water. I think that’s about 18 months.
Then you go work your tail off at each phase of nuclear power training. That’s where strong STEM performance at USNA and excellent study skills pay off. That’s it - you work hard, with all the other people from other commissioning sources (NROTC, NUPOC, etc.) sweating right beside you.