I know this is a much larger discussion, but may I ask your methods for getting so many airline points? That's awesome!
Also, random plug here but seems relevant, r/personalfinance and r/militaryfinance are great subreddits.
I use a credit card for every single purchase I can, up until a few years ago, I only used my Capital One Venture Card (double mile) 2 miles for every dollar spent. However, typically credit cards that offer mile rewards is super misleading, as you might think "Oh snaps! I got 30,000 miles saved up I can fly around the world 1.2 times!" But in reality, what you do is take off the last 2 numbers and you have $300 worth of an airline ticket. The return with miles is essentially 2% Cash back, but cash that's only redeemable on travel types of purchases e.g., hotels, airline, cabs, buss, train, etc. However, I'm actually planning on discontinuing my use of this card once I get down to Florida as USAA offers a Limitless Cash back rewards card with 2.5% cash back, however, that card is on a pilot program and is only offered in certain states, Virginia not currently one, but Florida is.
I also like the AMEX platinum, sign up bonus is great and it comes with great airport perks, but I personally haven't used it since I got the bonus. I use their Blue Cash Preferred card on regular basis as it gives 6% cash back on grocery's at supermarkets (however doesn't work at places that sell groceries and everything else, such as Walmart, but I believe it works at Walmart Neighborhood markets), it 100% works at the Commissaries. Gives 3% back at gas stations. I also have the Amazon Prime Store card that gives 5% cash back on Amazon purchases.
So, in a nut shell I use the credit card that gives me the biggest return on that particular transaction, payoff the statement balance every month or the whole balance. As long as you pay the statement balance, there is no interest incurred.
Purchasing a car and plan to put money down? Use your credit card then just pay off balance, boom HUGE rewards.
Also note, not all Credit Cards offer the SCRA benefits the entire time your on active duty to waive membership fees or lower interest rates, but Capital one and AMEX do for sure.
HOWEVER, my most important advice, if you do not have discipline and do not pay off your statement balances every month, then DO NOT do this, as the interest you will pay, most definitely exceed your benefits received.