I've been playing since I was about 13 or 14, and the best bit of advice I can give to beginners, especially late starters, is to decide what you want to do with it.
If you want to be able to (eventually) impress with your chops, to be able to perform other artists songs well, you need to absolutely hammer it practising your 4-digit fingering, learning your scales and chord transitions. Depending on whether you want to play lead parts on a lecky, or perhaps more classical compositions on an acoustic, skill will gradually come from the foundational stuff becoming second nature. And don't get frustrated with what you'll probably consider slow, arduous practice drills without much progress, 'cause the way it works is that one day you just discover you can do something out of the blue that was an impassable obstacle before. The human brain, and its relationship with learning how to use tools, is weird like that!
However, to be honest I never really learned to play that way, with highly-disciplined practice or any of that. In my early years of playing in adolescence, I mainly got stoned and messed about with chords and chord progressions I just felt sounded class, and used loads of 2-digit fingering, effects pedals, all sorts of little cheats to just enjoy myself hearing the sounds I was producing. It probably took me longer in terms of timespan to learn stuff beyond the basics, but what it did was keep me engaged, I learned to love picking the guitar up rather than associate it with technically-focused chores. What happens is, although it may well take you longer, you pick up a lot of the other stuff anyway, almost unconsciously, through joyous sonic experimentation. And then later on, once you've developed an individual sound, the stuff you've not picked up probably doesn't fit your style all that much anyway, it's needless frills, noodling for the sake of it with no real soul behind it.
So that's how I'd encourage a kid of my own to pick it up, and the same applies no matter what your age really. Enjoy actually playing, actually composing songs and shit, rather than 'getting better'. 'Cause that'll happen anyway - I have no idea why, but one day I went from playing with basically just 2 fingers running on the fretboard to 3, and then 4, and could more or less do it without having drilled it into myself. The easiest practice comes once you have a genuine feel for it, and love doing it. I bet that's why so many sack it off, because they haven't fallen in love with it first by just messing around for ages - foreplay, if you will - and all the sore fingertips and aching hand muscles and stilted-sounding Led Zeppish blues-based solos seem pointless. Your mind, body and soul will adjust to any instrument, with enough love and patience.
