Choose music in different styles. Trombonists have to be able to play well in band, orchestra, jazz band, choral accompaniments, brass ensembles, trombone ensembles, etc. Don’t play the same style in every ensemble. Each one requires a different approach. When you are unsure about the sound and style the conductor desires, ask her/him. Try to adjust to the desired style and don’t be stubborn when you receive a suggestion. The conductor is trying to make you sound better.