Just wondering if there are any accomplished guitar players in the forum. What helped your progress the most? Is there a Brian Manzella of guitar?
Everything depends on what you want to do. Accompany singalongs? Jazz? Classical? Shred? Do you want (or will you need) to learn to read notation?
In terms of what helped me the most - I started with a teacher who made playing and lessons fun. You're probably older than I was when I started learning, but I don't think its necessarily any easier to keep the motivation levels up when you start playing as an adult. After maybe 6 years of lessons, I realised I needed a new teacher to progress. And when I found one, he took me right back to square one and rebuilt my technique from the very basics, starting with how to sit and hold the guitar. Although that sounds frustrating, I don't feel like I wasted the time with my first teacher. Although I was back at the beginning - I wasn't a beginner, and I made much quicker progress than I could have made with no playing experience. Different teachers have different approaches - some will click with you and some won't. I had one teacher who had a fantastic track record with his pupils - but I was never entirely comfortable with his approach to teaching and drifted away. With the benefit of hindsight, I can see what he was doing and I can see the value of it - but it wasn't what I was looking for at the time.
This might not be a popular thing to say on a golf site - but I think learning the guitar without a teacher is probably more difficult than learning golf without a teacher.
Like most things - practice is essential. And the more consistent you can make your practice, the better. Starting out - if you can manage 20 - 30 minutes maybe 4 days a week, then you're off to a good start. Build up your practice slowly - strength and flexibility (and callouses) are at least as much of an issue as in golf, so give these a chance to develop. You can easily do enough in one session to make practicing the next day too painful to contemplate - which is quite counter-productive.
As regards the metronome - I don't agree that it's essential. Useful - but not essential. I played for 14 years before I had one of my own and in that time, rhythm was much the strongest part of my playing and musical sense. In terms of musicality, if you have the opportunity to play along with someone else then that's probably more valuable than learning to play along with a clock. But they are useful.
I dunno about "the Brian Manzella of the guitar" - but if you're interested in rock or blues check out Richard Daniels at
Guitar Instructions: Blues, Heavy Metal and Rock Guitar Instructional Books and Videos . To be honest, I haven't spent much time on his website, but I have several of his books and they are unlike anything else I've ever seen in terms of the passion and diligence that he's invested in his work. For someone starting out, I'd recommend Blues Guitar Inside and Out - but you will not outgrow it.
And, if you haven't already, read the Talent Code by Daniel Coyle.
And lastly, despite what you may have learned in golf, having a Method for the guitar is no bad thing. In fact, you might want more than one.
Good luck.