Records are helpful, but not a true indicator of an orchestral trombonist's abilities or responsibilities Take advantage of every playing-performing opportunity you can. It never hurts to know too much about trombone performance or music in general. Don't set you sights on only one particular job. It usually leads to a lot of frustration and disappointment. However, Don't practice only orchestral passages ad nauseum.
Mindless repetition leads to very boring presentations.
For tape auditions, take your time and produce a tape which pleases you. Be sure to listen to it, and don't submit something with which you are not satisfied. At live auditions, try to project a blend of well founded conviction, with the ability to be flexible. A conductor needs to know his players are strong and confident, but will be willing to accept his suggestions. Don't let your mind wonder off.