Water, lunch, good walking shoes, sunscreen, and car-pool money. Some other trips may require boots and other equipment. If you're not sure, ask the outing leader for that trip. Radios, firearms, obscene behavior are prohibited on all trips. If you have any problems with behavior, let the trip leader know and the problem will be addressed.
Some leaders meet at a museum, restaurant, etc to car-pool.
The trip does not officially begin until you are at the trailhead. Each leader has a different place to collect before starting the outing. The leader will let you know when you sign up for an outing. Dogs are not permitted on outings unless advertised. They must be on a leash or they will not be permitted on the outing.