Totally self-taught on all the instruments I noodle
with
and after 20 years on guitar I can play all the notes in
the Smoke on the Water riff
seriously,
I'm self-taught on guitar, mandolin, bass, keyboards
though guitar is really the only one I'm any good at.
I started with a bunch of books with chord windows
of my favourite (easy to play) songs and went from
there.
My best advice would be to expose yourself (not that
way) to as many different styles of music as possible
(funk, rock, prog, folk, blues, classical, jazz) all will
give you different techniques you can employ in your
own music.
A salutary lesson for me was playing with a jazz-funk
band in the mid-90s - it taught me completely
different disciplines and techniques which
broadened my playing massively.
IMO opinion there's nothing worse than hearing a
player who's technically great but utterly locked into a
single manner of playing.
Other advice? Explore your instrument (not that way
) I mean don't be afraid to make stuff up. Try
framing chords different ways, put you fingers on the
frets in unfamiliar ways. Don't be afraid to
experiement with articulations you've never seen in a
book. I don't know the name of most of the stuff I
play, I just play what sounds melodious and 'good'
couldn't tell you if it was diminished, augmented or
whatever.
Self-taught often means more willing to break rules
for me. I once knew a classically pianist who could
play beautifully but could not compose because her
teaching was so rigid that she was unable to
express herself unless it was by playing music
printed on sheets - terrible.
Get a bunch of chord window books, start practising
the tunes and within a year I guarantee you'll be
trying to figure out your own voicings... go for it