I am 41 years old and did not even understand what a chord was, in the context of guitar, until about a week ago. I talked my young son (9 years old) into taking guitar lessons and then decided, "what the hell, I've always wanted to play", so I bought a guitar for myself and I'm going to work with him on his lesson homework and also try the "learn at home" method using online resources. Luckily, I have a friend who is an amazing guitarist who I can annoy with some of my newby questions, but thought this site might also be nice, so I can get more feedback.

Right now, I'm a bit intimidated by my lack of finger dexterity in my fret hand. I'm told that comes fairly quickly if you practice regularly, but it seems like a huge obstacle right now.

Also, I ordered my guitar online (don't judge me). I want to attempt to tune it myself, and it comes with an eTuner, but my friend also suggested I take it to a professional to have it "set up". I am not 100% sure what that entails, but he mentioned that string height is a major factor in making the guitar easier to play.

Any advice for an old guy just getting his toes wet is appreciated.

One initial question - I picked out a song that I read was relatively easy to learn as the first song for the new guitar (House of the Rising Sun). Is it silly to attempt to learn an actual song right away, while also doing the practice required of an absolute beginner? I have a basic understanding of reading tabs already.
Its never to late to start playing! So don't worry about your age!

My teacher told me he has a student that at 84 years old is just now learning the piano. Id say you are starting pretty young in comparison. So, just play your heart out man. That's my only advice.
Just another Sheep in the design of the Almighty Machine.

Gibson 60s Les Paul Tribute (Sunburst)
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What helped me a lot in the beginner stage was Instructional videos and books. I would recommend guitar for dummies. It will teach you very basic things that beginners need to know in great detail and it will develop your technique. That combine with a good teacher (or friend) helping you out, should help greatly. Hope this helps. Good luck!
I've been watching Justinguitar.com videos. I think I understand the basics of playing simple songs and reading the tabs. Now it is a matter of executing what I've learned (the easy part, right?)

I am most concerned (as I think I already stated) with getting the dexterity in my frett hand to form the chords and to move from chord to chord. The rest of it seems like it will be easy with practice (but I acknowledge that I could be way off).

I have always been pretty good at memorizing things, so I think actually learning the chords and remembering the progressions will come quickly for me. The mechanics of the left hand...I'm not so sure that will come fast.
You got to start somewhere and it is a good idea to play a simple song as a supplement to your otherwise might get boring beginner guitarist workout. lol. And yes, do start with House of the Rising sun. Familiar yourself with the chords, chord changing , right hand plucking, as usual, start slow.
Oh well, oh well, oh well