I'll be real with you. You will be challenged, especially your first year. I'm not in engineering (I am a STEM major though), but I have been fortunate to get a 3.6+ each semester so far. I'll give you advice on what I've done to have these types of grades at an SMC.
1. Make a 4 year degree plan.
I don't know about AROTC, but in NROTC, we are required to make a 4 year degree plan, listing all the classes we would be taking each semester until we graduate. (This way, NROTC is for certain it will take us 4 years to graduate). The asterisk to this is that the degree plan is not for certain, but it does give you a general outline of what each semester will look like leading up until you graduate. I don't know about A&M, but it is common where I go for students to load up on 20+ credit hours. I even know someone that is taking 26 hours this semester. Remember, you are also taking ROTC classes, which tacks on another 3+ hours a semester, and I know for sure as an engineering major you will be taking quite a bit of classes to get an engineering degree.
What this does for me is basically give me a map of how well I need to do each semester. You will know from word of mouth, which classes will be harder than others, especially as you start getting into your major down the road. For myself, if I saw I was 20 or more credits for a semester, I automatically looked for summer classes to take at my local community college to lighten that semesters load (the Army does not pay for summer classes however, so keep that in mind). Although I want to work hard in all my classes, I also don't want to be completely engulfed in academics to the point I'm so deep in water that I can't go back up for air.
Also, while it is important to talk to your academic adviser, make sure you look stuff up on your own. (Look at your course catalog. See if classes alternate every so year. See if you tested out of some classes). While my adviser is very smart, I've disputed over things with him in my degree plan, and it turned out I was right because of the research I did.
2. Make a schedule of each semester.
Whenever I have registered for classes, and know my class schedule, I make a spreadsheet. It dictates my life in that I know when I to go to classes, when I work out, when I go to this extracurricular activity, when to go to work, and so on.
3. Start off college awesome.
Your first academic year is probably the most crucial year. If you do bad your first year, it will be harder on yourself to bring yourself back up. I made it my prerogative to start off my first year of college right while classes are semi-easy (before delving really into my major), and it got me to a 3.7 cumulative GPA.
4. Conquer through adversity.
You can't be afraid to fail sometimes. Things will happen, and you just have to push through them. I think of college as my first step of training as a military officer. You will fail, but it is learning from those failures to succeed in the future. Your first year in the corps at A&M will be hard. Trust me, I've been there. Time will be taken away from you, but you will have to learn to push through it. Embrace the environment, but don't let it conquer your life. Remember why you are there, and that is to first and foremost get a college education. Anyone telling you otherwise is wrong.
5. Seek help.
Whether that be with physical fitness, emotional or mental health, in academics, there are resources at your disposal that you can take advantage of that many students never do. I make sure I go to tutoring sessions, or Professor Office Hours daily.
6. Relax... Then pedal to the metal... Relax... Then pedal to the metal...
How I approach my weeks at school is to absolutely work my butt off at everything I do, whether that be focusing in classes, working, studying, more classes, and more studying.
But when the week is up on Friday, I relax... I'm not one to party, but I make sure to relax, and not even think about school or anything else. I'll watch a movie in my room. Watch football. Sleep..
Then on Saturday, I slowly work my way into working hard again.
From what I heard at A&M, they stress academics probably more than any of the other SMCs (not for certain, but their corps did average a 3.0 GPA whenever I spent the night with the Corps). You will also have the weekends to yourselves during your "fish" year, which is HUGE- don't let those weekends go to waste though.
Take the advice for what it is. I was in your shoes worrying about making good grades amongst everything else my first year at an SMC, and I still worry about making good grades and everything else today. You'll find how you best work. Just remember as long as you as hard as you can (not just work hard but as best as you can), that is all you can ask of yourself.