Improving my chances of getting in to the USNA?

<p>I am currently a sophmore in highschool and I saw on the website that the minimum age for applying to the naval academy was 17 and I will be 17 September. I would like to know my chances of getting in I have mostly As and Bs in school but I do have classes I struggle with and get a rare C or D. I am on the varsity swim team and varsity track team. I will have all of my science credits required to graduate at the end of this year. I would like to know what other science class i should take next year for bettering my chances. Also since I will be 17 in September when would be my earliest time to apply because I have read that the earkiest you apply the more likely yu are to get in. I am going to go into rotc next year if I can and would like to acheive my an eagle scout rank also for boy scouts. Are ether of those going to improve my chances? I never saw my self in the military much less the navy but the navy has grown on me my dad was in the navy on carriers and one of my grampas acheived the highest rank an enlisted can reach and my great grampa on my dads side was an fighter pilot and fought in a war cannot remember what the name was but the navy and military goes back in my family and I heard that this helps yur chances of getting in is that true?
I would appreciate help and/or info from everybody</p>