Find a large flying club that will let you be an independent contractor, charge what you want and keep it all (other than monthly dues). Yes resumes, business cards etc. You'll need to actually learn to fly and teach some techniques in the planes you'll fly. Plan on maybe 6 to 9 hours of dual for that. Use the fact that you're going to spend some money there as another reason to hire you.

Get some mentors (life long CFI's, guys that are in other professions and instruct on the side, and yes, even young time builders).

The best students are successful professionals or aspiring airline pilots with well off parents to pay. The reality is that you initially won't be as good as an instructor as a kid who's been flying just Cessna's for the last few years, but you'll improve rapidly and it doesn't matter. Market your extensive military experience to your prospective students and thy wont even know that you're actually quite new at instructing GA. Many will be willing to pay a premium.

Charge from handshake to handshake (ie ground time too) I don't know the going rates but I'd guess at least $45 per hour.