Mozart - Tuba Mirum
General Advice
This is one of the most common orchestral excerpts for tenor trombone. Notes should be full value to fit the orchestral style. Make sure your intonation, body of sound, and dynamics are in check. I highly recommending listening to this excerpt in the context of the piece, with the vocalist. I also recommend recording yourself and listening back to find areas for improvement.
Resources
Full Orchestra Excerpt Recording - London Philharmonic Orchestra
Full Orchestra Excerpt Recording - Martin Schippers
Masterclass with Vienna Philharmonic Principal Trombone, Dietmar Küblböck - Carnegie Hall