Radio? Music Blogs? Randomly on YouTube? Spotify? Pandora? DatPiff? MTV? BET? Late Night Shows? Word Of Mouth From Friends? Randomly Clicking SoundCloud Links on Twitter? WorldStarHipHop?
"Similar artists" on Last FM & Spotify
Genre tags & high ratings on Rateyourmusic.com
Music blogs (I pinned a bunch to my Facebook and other social media)
Music recommendations from friends