Hey man,
Fellow military guy here. The biggest thing for you is going to be the following:
1. SAVE...SAVE....SAVE. While your at basic and literally getting everything paid for, your monthly expenses should be negligible. You wont be making a lot initially, but your opportunity to save your money and not waste it like all the other privates on hookers, booze and tattoos will set you on the right path.
2. Within your first year you should be able to save between 7-10K. Do this for 2-3 years and by the time you are an E-5 (eligible to live off post, unless you are married which is a whole other conversation ) you should have a good nest egg of between 20-30K that you will be able to use as your reserve fund.
3. When you finally do invest, go for multi-family (2-5 doors) near where you will be posted (being close is key, especially since you will be really busy in the military) that you can self manage. Purchase, collect BAH (which depending on where you live should be around an additional 1K) and then your "tenets" in the other attached homes will be paying your mortgage while you now can save the entire BAH per month. Now in effect you can double the amount you save per year, saving near 15-20K a year. Allowing you to purchase your next property much sooner.
4. Rinse, repeat, profit