That being said, I'm not here to discourage people from the profession. I know quite a few instructors and to a man they all rave about how much they truly love their job. Many of them get to hang out on the course, set their own hours, make pretty good money, and still get to play golf quite often. This is a lot different from the assistant pro who works 60+ hours a week, makes peanuts, and doesn't get much time to play golf.
The unfortunate part of the profession is that at its core, the success depends on how well one can market themselves. I do not consider Leadbetter a great teacher because his failure rate is very high, but he's been a guy that has marketed himself brilliantly...in fact better than any instructor ever...and he's the most famous and wealthiest instructor of all time. OTOH, I know some people that really know the swing, but are so poor at marketing themselves or reluctant to market themselves and they don't make a lot of money. The big thing I would tell anybody is that do not expect to get a luxurious gig like Leadbetter or Haney or McLean have. Maybe in the long run if you play your cards right and have a lot of luck on your side.
The other unfortunate part is often times the people that make out well in the profession were good golfers either in college or may have made the Nationwide or even PGA Tour. Or they have a beautiful golf swing and hit the ball quite well. It doesn't matter if they know what they are talking about or can explain it properly, as long as they have a good swing they will often draw attention.
With those things aside, I highly suggest becoming an Authorized Instructor of The Golfing Machine.
However, I think there's more to it than just reading the book and taking the classes. In fact, I think it would be impossible to just pick up the book and understand it. But, if you become an AI of The Golfing Machine, its a great way to learn and teach the swing, a great way to make connections, and a great way to give yourself some credentials.
The best way I believe of going about learning TGM is to first read Bobby Clampett's 'The Impact Zone' book and read Jeff Mann's Web site (http://perfectgolfswingreview.net/)
Both are simplified versions of The Golfing Machine. The Impact Zone doesn't really even go into TGM's lingo and jargon, but explains the very basic geometry of the golf swing (Clampett's 'ball flight laws' are outdated and incorrect, but other than that it's a fine book). Mann's Perfect Golf Swing Review incorporates some other teachings, but it has plenty of TGM info in there in a simple manner to understand. Meanwhile, I would find an authorized instructor (you can find one at http://www.thegolfingmachine.com/) and start working with him to understand a bit of the process.
Now, you should be ready to start to understand the book. In the preface of 'The Golfing Machine' it goes over the order in which to read the book. I suggest that as you are reading the book, purchase Peter Croker's 'TGM Downloads' (http://www.crokergolf.com/TGM_Downloads.htm) to help explain the basic parts of TGM.
After that, you should be pretty much ready to take the the Bachelors version of the courses. You can go even further and earn the Masters level or even Doctorate, but if you do not go that far it's not a bad thing.
All in the meantime I would suggest the following sites to help with TGM and golf in general.
Also a good instructor will have a quality camera that works well in slow motion as well as a quality instruction software program.
I also highly suggest to basically learn everything you can and then decipher what the good stuff is and what the bad stuff is. Learn as much as you can about putting. You'd be surprised on how much pros work on their putting with their instructor over their golf swing. Learn as many different swing methods as you can (which is really what TGM is about).
As far as promoting one's self, I suggest getting a Web site with a forum. Answer questions. Do some YouTube videos explaining some basic instruction.
One of the greatest lines I have ever come across is 'a true wiseman has more questions than answers.' If you follow that line of thinking, I believe you will be a fountain of information for your students and become the best instructor you can be.