I joined a brass band and was given a 2 valved Yamaha Xeno. I've been told I need to be the loudest in the band, while maintaining a good tone. Any tips on how to do this?

The key to playing loud is by using faster air. But at the same time, be sure to keep a steady column of air to keep all notes even. Also try to stay relaxed with your body and maintain a proper embesure.