Here are some simple thoughts about how to behave.
Be on time. No one cares about your excuses. The rule is, "if you're not early, you're late".
Allow for the worst traffic possible. Obviously no one wants you there an hour early, so if that happens, just park and explore the neighborhood.
Don't talk too much. Keep the greetings simple, friendly and short.
When the session is over, LEAVE. Some people think it's ok to hang out, it is not.
If they are telling jokes, by all means laugh, but this is not an invitation for you to tell jokes too.
When you flub, just say pick up and go back to the top of the sentence. Do not apologize or explain why you flubbed, no one cares. Just fix it.
Be a good listener. Observe how the people behave and conduct themselves. They are there to do business as are you. Everyone wants to do good work and get good work from the voiceover artists. We can contribute to the projects success and our own success, by watching, listening and being smart about other people.
Have a great week.