Could I please get some Aviation Career/Education advice for leaving active duty/joining the Guard?

LTJG (Join to see) With your interest in Aerospace, I would look at SpaceX, Boeing, and the other Aerospace companies to see what openings they have and what their educational requirements are. I would not rule out Navy OCS. What ever you decide on, you will be successful. Semper Fi.

I'd look into Warrant Officer Flight Training. I've had both aviation officers and warrant officers tell me that you only fly until you're an O3, after that, you'll mostly be behind a desk, flying on a rare occasion. On the other hand, as a warrant officer you have the opportunity to fly for the rest of your career. I would also look into the Resrves, as it has the same things as the Guard, as far as what you're looking for. I know that there is a Reserve Aviation unit located in Colorado. As you've already passed Marine boot, you wouldn't have to do Army basic training. If you were to get accepted, you would go to Warrant Officer Candidate School and then to Flight School. There's a guy in my unit right now putting in this packet, he's a mechanic and his odds are good (one of the ECS civilians he works with was a mechanic in the Reserves and is now a Flight Warrant) so there's no reason that you shouldn't be able to get it.

My advice would be dated since I entered aviation during Vietnam when it was easy to get into and easy to build time. I went in out of HS, and could have flown commercially immediately after Nam. I stayed in the military for over 8 yrs after Nam. It is important to note that I was single during that entire time - AND for half of my civilian schooling time. There's no doubt about it, family life was GREAT, but it DID make schooling and Guard requirements tougher......... It was also fortunate for me that I had saved money during my active duty days, and my (future) wife was an RN........

I retired 20 years ago from the National Guard, which was easy to get into because I was already quite qualified, and I only needed a slot. When I got out of active duty the first time, I went to school. I ALSO used the GI Bill (5+ years!!! - if you knew how to work the system's "fine print") to get every civil aviation qualification that I could, and THAT, along with my military experience made getting later civil employment quite easy. When the GI Bill money started getting low, I went into the part-time Guard for some really good (weekend/summer) money to help me pay for more civilian schooling. I was part time in the Guard for five years, flying civil aviation - before I found a competitive opening for a full-time AGR position, at which time I left civil aviation to finish up my active duty career. After I retired from the Guard I got back into civil aviation in the civil EMS field.

IMHO, the military AFTER Vietnam was not a huge time builder, but it WAS excellent for getting aviation schooling of all kinds. Safety, Training, instruction, maintenance, multi-engine, etc. I was fortunate that I was able to get qualified in many airframes with the Military - not sure how much you can "branch out" in this day and age. I'm not sure what civilian flight time requirements are nowadays, but it's mostly based on how insurable you are based on experience. You probably should still be able to take your military flight school records to the GADO office to get your commercial helicopter with instrument. Once you get your commercial along with some required flight time, you could perhaps build time quickly by becoming an instructor pilot, a sightseeing pilot, or a FAA part 132 commercial pilot. Fixed-wing training and flying is cheaper and a good time-builder. Get the ATP as soon as you qualify, and for me, getting a "legitimate (not a quickie) A&P license was very benificial. IMHO - the most hazardous flying was EMS, followed by FAA Part 132, then maintenance test flying. The easiest (though "boring for me") was the flight instructor and sight-seeing, perhaps b/c it was highly controlled and repetitive. It depends on what stuff you get into on that, however.

Alas, "old age and infirmities" crept up on me, and, my aviation/A&P interests today lie in flying drones, farming machinery, and "ultra-light" during my "retirement" years.......