This is a fun topic. A few watersheds in my development as a player and thinker over the years:
- Learning the difference between overdriven power tubes and preamp gain distortion really helped me find my way to sounds I like. My first-ever amp was a Peavey Backstage Plus which had this utterly craptacular fizzy, buzzy, saturated preamp distortion that I would dial up to ten because it really made me feel like I was playing ELECTRIC GUITAR, MAN!! I suspect many new guitarists go that route. Anyway, I lived in the Army barracks at that time, so I could never really run up any appreciable volume for fear of being defenestrated by my fellow soldiers, but screw it, I was having fun sounding like sh!t. And so it continued through a couple different iterations of solid-state gear and effects. Eventually, though, I got my first tube amp - a Yamaha T50C - which was also capable of very high gain sounds, but a world away from the Peavey and Marshall noises I had been playing with. And I learned that I was much happier making sounds with the gain dialed up to 3 instead of 10 on the dirty channel, and with the channel master volume bumped up higher. And I developed the habit of EXPLORING the amp's capabilities instead of just going balls-to-the-wall in the preamp and then adjusting the master to keep from pissing off the neighbors.
- Contemporaneously with my discovery of power-amp overdrive, I discovered how guitar-volume-knob adjustments could also provide a broader spectrum of tones along the distortion continuum. So valuable.
- The Telecaster and the P-90! I somehow made it through my first 20+ years playing guitar without spending any time playing a Tele or soapbar pickups. But I picked up an Aerodyne Tele (standard Tele bridge pup, P-90 neck) for a song from a young police officer who was selling gear and emptying his music room to make way for the baby he and his wife were expecting. This was a double win. The simplicity of the Tele as a music-making tool and the mutability of the P-90 helped me further expand my ability to make sounds I found pleasing.
- The joy of playing rhythm. There was a time I was a weekly attendee at a local dive bar blues jam. This was in the wake of the Marriage 1.0 airplane flying into the mountainside, moving to a city I had never lived in, flaming out in my professional life, and miscellaneous other disasters. So getting a chance to make music and commune with fellow sufferers really helped me keep from putting my head in the oven. I'm nobody's idea of a fleet-fingered technician, but I managed to establish a role for myself as the guy who know how to play supportively, with appropriate volume and complementary chords and rhythm choices. So while the guys who wanted to get up and shred would rotate through the night at 3 songs apiece, I was often invited to play an entire hour-long set because I didn't need the ego trip. I'd take a solo or two but I found that music as a cooperative endeavor was how I work best.
- The pentatonic scale. I mean it's a total basic for western music and blues/rock/jazz in particular, but learning its various forms and how to maneuver between them, as well as how to supplement with chromatics and so on, opened up the neck for me and facilitated a lot of ear-learning.
