Once you get to know some of them, they will more likely listen to what you have if you can establish a solid relationship with them. Sometimes they pay a flat rate and along with that you will get performance royalty money through ASCAP or BMI, but generally you may only get performance royalties. If you have multiple placements out this money can add up fast.
One way to try and get placements is to subscribe to the Hollywood Reporter online. They have a list of TV shows and movies that are currently in production. They generally list the names of the companies producing them too so you can call and ask how to get in contact with the music supervisor of that particular project. Keep trying and never give up and things will happen.
Artists and bands be sure to submit your music at these radio networks.
www.hardcorejamz.com (Playing Hip-Hop and R&B)
www.hardcoremix.com (Rock,Pop,Country,Jazz,Electro,Gospel and more)
Submit music on either site