Being somewhat new to the biz, someone might have some useful advice for me:

Say, I've created an excellent, creative cataglogue of gaming music and I was looking to freelance the work. Who do I approach to begin the process?

What about a web-site in a commercial sprite-lib format? You could throw together an online portfolio where people download samples of songs, and then if they want to use those songs in their game they must pay some nominal licensing fee. After they have paid this fee, the song is marked as unavailable and they effectively own it. In this way, you have distributed it.