I'm fortunate enough (having played most of my life, gone to a music school, and now working as a musician) to have many amazing musicians as friends. Musician friends must never be overlooked as a valuable asset in finding good new music.
My second advice for finding good new music is to research the artists you like. Especially if it's in a style you're not super familiar with. The research can open the doors to hearing more names, and you can follow those names up and end up discovering something great, something overhyped, or something perfectly mediocre.
A fantastic blog for Japanese music you can't usually find is
Hitoshizuku. This guy finds and recommends killer great stuff that seldom shows up on Oricon. I've grabbed almost everything he's posted and not deleted one album (and I delete what I don't listen to). He's also a big SR/TJ fan.