I'm trying to begin an indie record label. I already know how to get music onto iTunes and Amazon Music, already have the knowledge to build a site and a general idea of what it should look like, the legal aspects of record labels, etc. The one thing that I am unable to find any good information on is advertising music. The only real advertisements I see for music are either for concerts, or for new albums on the front page of iTunes. I thought maybe about trying to contact others about putting my label's music in their media (videos, games, etc.), but I'm still not entirely sure that would be an effective way to advertise my label's music and for me to earn a profit.
So, question: What are some common ways to advertise music?