Recommendations from friends, suggested videos on youtube, related artists on Spotify, occasionally suggestions from Facebook, and gigs with multiple bands on the bill [you go to see one, you end up liking several more].
Oh yes, and sometimes I'll hear songs in movies/ TV shows that I like, and I'll discover new music that way.
Also that's a point, sometimes I'll check out stuff that's been reviewed in magazines/ on music websites, though not that often, because they're usual inaccurate, highly subjective, and pretentious.