which leads my question. if you had to start over and use just 1 'method' (niche sites, facebook, youtube, etc) to concentrate on and get things going, what would it be?
I wouldn't use any method.
I have 15 years of skills that someone just starting out doesn't have.
I could do multiple things.
I could run some fb ads with opt-ins and webinars and pitch SEO consulting for $5k/mo. If I spent $2k-$3k in ads I'd get at least 1 sign-up. Another 4-5 clients and I'm at $30k/mo with 5-6 clients to service.
I can only do that because of *multiple* skills. I can sell via text. I can sell on the phone. I know how to run and track ads. I understand LTV. I know how to use so many tools to make all this easy. I'm good at talking to sell and talking to teach. I'm good at writing to sell and writing to teach. I can write articles, I can write books, I can create video courses and I can help clients rank over the long term with a really good on-page content strategy, technical on-page SEO and link building plan. All of that means I can get 4-5 $5k/mo full service clients pretty quickly. The average person is lacking all of those things, the most important being fulfillment.
There's a reason millionaires rattle on about reading and learning and it isn't to sell you courses. It's because it's the ONLY thing that stops you from being poor. Rich people are rich because of their skills, not because of their wealth.
Or for me.. lol.. What I would do is go and buy some auction domains, set them up and sell homepage sticky's.

Until that stops producing results in SEO that's my go-to. It's far more enjoyable to sell links than it is do full service SEO.
But there are countless things I could do. 99% of them involve running ads and setting up email to webinar funnels and/or email to call funnels. I wouldn't do anything else. These things are easy for me to sell with and they are instant money.
The more important question is what should you do, which is to write down all your skills and try to find something you can leverage with those skills, and while building something, be learning more. You can't go wrong with sales and copywriting.