A few ways: From here at ASR; 'Music Reviews and Discussions', from my friends recommendations now defunct blog 'aurgasm.us', bandcamp.com, loudersound.com/prog, sonicboom, 4 producers and listening to radio paradise 'global mix'. At times I've heard music when out socialising/shopping/eating and I've asked who that is; I've always had a positive reaction and usually a conversation about the music ensues.
Radio Paradise is pretty great.
When I was a wee lad: AOR FM channels and simply milling about at the record store!
Sometimes, buying a record because the cover intrigued me. (There can be stinkers, too.)
Friends, of course.
Also, going to see bands I had never heard of, or even opening acts for acts I do know. (I've actually been turned into a fan of acts I thought I didn't like, but their live set was so good, it changed my tune!)
Hearing DJ sets, sometimes even what's on at a good bar or lounge.
Also, nerd, reading album credits and then seeking out what else the personnel have been on or even what the producer has done.
Recently, the "Other things you may like" listings from streaming services.
I've even found some at Hi Fi shows, which is weird...shows seem to favor Hell Freezes over, Diana Krall, Patricia Barber, and Norah Jones. But, sometimes, paydirt!
Fun topic!
Example: 14 years old, listening to KGLR in Reno, Nevada. They did a "play an entire album" thing at midnight on some nights, and on the night of May 2nd, I heard Rick Wakeman's "Journey to the Centre of the Earth." So, I popped down to the record store the next day, and it wasn't there! It was release day and the shipment wouldn't arrive until later that day. So, I waited. While I was waiting, the coolest clerk on the planet played "Bryter Lyter," and I was smitten...by both the album and the young woman. So, I bought the import (very exotic and pricey in those days...like, 6 bucks!) and the clerk then turned me on to "Pink Moon." When the shipment came in, there was only one copy of the Wakeman album....and it was mine! The next week, I ordered the import of "Five Leaves Left." 6 years later, I was in Fort Collins for grad school, and I played "Bryter Lyter" in my residence hall room, and a girl popped her head into my doorway and said, "Nick Drake!" So, we went to dinner and then dated. Life turns on a very small point with a big wheel spinning out from there...love, work, everything can happen based on small little events.