Respect your fellow section member's choice of solos. Don't play during his, and he won't play during yours. Solos are to be mutually agreed upon by the entire section, and do not necessarily have to be written in the music. Your music is only a rough guideline for you to follow. You do not, by any means, have to play exactly what's written, as long as it doesn't sound too bad.
Harmonies are always welcome.
These rules do not have to be followed exactly. They are only a help in learning to put up with thw hassles you will encounter in everyday band.