There was a GREAT magazine in the 1980's called GIG..it was a really great publication that covered many areas to help the working musician....the quote below always stood out..hope you enjoy it as much as I have:
"A professional musician is someone who knows how to listen, is sensitive to the musical personalities around them and is AGRESSIVE IN THE BELIEF IN HIS/HER OWN ABILITIES. A professional does nor overplay and understands what it means to be a team player."
Lots of luck!!! As always, contact me with questions and comments....