You are getting some great advice. I could only agree with all of it so instead I'll give you some info about my DS that received a type 1 AFROTC scholarship last year so you can see what successful applicants had on their 'resume':
- 4.2 GPA (3.9 UW)
- 8 AP courses (5 up through Jr year which was counted for AFROTC I believe)
- 4 year varsity swim (Cpt Sr year)
- Eagle Scout (and all the leadership and community service that comes with that)
- Maxed out on push-ups and sit-ups, and got solid run time for PFT
- Noted various accolades and awards (National Honor Scholar, National Hispanic Merit Scholar, etc)
- His school has something called Excalibur Knights which is for top performing kids not just on GPA but well rounded abilities (sports, leadership, etc). They were seen as 'leaders' of the school (had to confirm no drugs/alcohol use, and were generally role models) and went to area middle schools to speak to the kids about doing well in school. I see this as any sort of leadership position via club or other group at the HS that your DD could join in Jr year.
- SAT 1480
- Seemed to do very well on his interview
- Mechanical Engineering declared major (AF in particular wants technical majors and is a major factor for scholarships - in fact a friend/cadet of my DS, lost his scholarship when he went from MechEng to liberal arts major after his first year).
I will also add - my DS was VERY shy growing up. Sounds very similar to your DD ("demeanor is reserved though hardworking, and attention to detail"). He didn't really come out of his shell until his Sr. year. The thing we noticed is that when he began to talk about something that he was passionate about, he would light up and do very well (in presenting or speaking with/to adults). Sort of a no brainer..... He went to Philmont Scout ranch one summer during his Scouting career and was the best time of his life. He had to deal with some adverse situations there and help his crew through it. When talking about that he just loved it so much he did great so he planned to use some of that during the interview to talk about how he stepped up and lead his crew (flash flood type of rain storm while on the trail, etc). So my one piece of advice is to get your DD to find the thing that she feels the most passionate and comfortable about and begin to leverage that as a way to help her do well during the interview and answer questions about leadership and how she overcame a difficult situation. That helps make it much easier for them to talk through it and do it with confidence.
I would also make sure you look into the DoDMERB medical history regulations since that is something that you don't think about until later. If there are any possible DQ items in your DD's past, you can begin to look into adjusting things (i.e. stop the use of systemic (oral) retinoids for diagnosed acne, etc) to help ensure that medical approval is received (you need that for a scholarship). There are a bunch of threads on this and you can find the details online as well.
Sounds like your DD is well on her way. Best of luck to you both!