It's also a good idea to park your vehicles headed back toward the entrance in case you have to leave early in order to minimize headlight trauma for those staying later. Parking lights are tolerated if you have to leave. If headlight use just can't be avoided, it's not a capital offense. If you have to use them go ahead. We'd rather lose night vision for a while, that have someone run over the telescopes.
Many people find that listening to music while observing enhances the experience.
Keep it low or use headphones. Always ask permission to view through someone else's telescope. Most of us enjoy sharing our toys if we're not busy working on an observing list or doing astrophotography. If there's some special object you like to see, just ask. Remember that we are guests on someone's private property and that these sites are not easy to come by.