So because I'm doofy I made on my iPod a playlist for each of my characters. It helps me to get into the proper mood when drawing or writing for them. The playlists are made up either of music I feel the character would actually like, or just songs that make me think of them.
Aggie has anything edgy or angry or punkish, and anything country-sounding (since I don't have that much straight country on my iPod unfortunately )
Clarabelle has about all of my popular music, and a lot of '50s, '60s, and '70s pop music. Anything cheerful and positive.
Joseph's soundtrack has a lot of classical music, anything melodramatic or tragic sounding. I wanted a lot of that sweeping, raw emotional type feeling for him.