GoNavy ...congratulations on thinking ahead and your early interest in the Naval Academy. I am believer that starting early and at least being aware of Service Academies and what they are looking for is very helpful, as it gives you the opportunity to be proactive and shape your application from the beginning.
The first bit of advice is to learn as much about the Naval Academy and Admissions process as you can, starting with the USNA Admissions webpage. You will see CAPT MJ's admonition to read it thoroughly, including all drop downs , etc. on this forum repeatedly -- and for good reason. The USNA Admissions website is the only "official" answer to many questions you may have. This Forum, and other online resources you may find, provides good insight but I would caution against over reliance. There is a saying at USNA that you live by the gouge, and die by the gouge. For the most part, the information on this Forum is good, and many people here will give you their views on what goes into a successful candidate, but you should recognize that each candidate is an individual, and what works for one person may not be the secret to success for the next person.
The Naval Academy (and other Service Academies ) is looking for well rounded candidates with an exemplary background in academics, athletics, leadership and community service. One of the documents you will find on the Admissions website is the Class Profile for the latest classes. You can use this for guidance in developing your own plan for making you application as competitive as possible, but again, keep in mind there is not single secret path to success. You have a somewhat unique circumstance, attending middle school overseas, so some activities may not be available and other activities may not translate to activities in the US. However, if you stick to the overall objective of developing a strong academic, athletic, leadership and community service record ... you should be fine. (As an additional note, while I have never dealt directly with an overseas applicant, I would encourage you to maintain contacts with a State of Residence in the US so you can apply for Nominations from a MOC, otherwise you could be limited to a Vice Presidential nomination. In addition, I would expect that ACT/SAT' scores will be perhaps more important than normal, as Admissions may not be as familiar with overseas schools at they are with the more traditional applicant.
Finally, you are still young ... while I applaud your maturity in seeking information about the Naval Academy early and I encourage you to pursue your dream, you should shouldn't become so focused on getting accepted to the Naval Academy that you give up the best school years. In other words, get involved in activities you truly enjoy instead of activities that look good on your application. If the two overlap --great. Finally, if your goal is to serve the country as an Officer in the Navy (or other services), keep in mind that there many ways to get there, so always have a good Plan B etc.
Best of luck to you.