The complete list can be found here, but I offer a few of my favorites (with my own comments in bold):
Particularly contemporary for the NJ Symphony: do NOT hire a resume-padding pedophile as your orchestra President. This cannot end well.
Aimed surely at the Minnesota Orchestra: do NOT embark on multi-million dollar renovations of your hall while simultaneously complaining about how much ‘the help’ are paid.
For all of us: do NOT allow your Music Director to program Overture/Concerto/Symphony for an entire season. Fire that person.
do NOT hire a Music Director based on one set of concerts. Ever. The only thing worse than making a rush choice is making a bad rush choice. Take your time. You are turning the reins of your orchestra over to someone who needs to be able to go from Bach to (God forbid) Bieber and everything inbetween. And fergodsakes, please make sure that person is at least old enough to shave. (an interesting thought).
To musicians: do NOT be one of those people who show up, sit in the back of the section with a sour look on your face, and complain all day about your job. No, for the vast majority of us this music thing is not an easy life but it beats the hell out of working deep sewer. People pay us to make music. We are running the greatest scam in the history of the world.
do NOT put anyone into your orchestra who cannot play Mozart. Period.
To Conductors: do NOT constantly program overture/concerto/symphony. If you do, you deserve to be fired.
do NOT become Music Director of 5 orchestras simultaneously. One is enough. Pay attention to that one and do your job well. It was good enough for Ormandy, it should be good enough for you.
For the greater good: DO love what you do. If you don’t love it, get out. Please. Music is too beautiful to be taken for granted.