How to clean and maintain a sousaphone?

I'm learning to play sousaphone this summer and I'm playing it in my high school marching band. The thing is, I've played clarinet since sixth grade and I have no knowledge of brass instruments. I've brought the mouthpiece and the pipe thing that goes on that home to practice buzzing. But the problem is... It smells... interesting and it's dingy on the inside of the mouthpiece.. How do I clean it?