If you are taking minors on your trip, the top of your checklist should read "Permission Slips." Make sure you obtain signed permission slips for all children allowed to go on the trip. The permission slips should include an emergency contact number for the student. The informative permission slips should also direct parents to either pack a lunch for students or include money for lunch on site. Collect the permission slips in advance and bring them with you in a file folder on the field trip.
Whether you are going to a museum or a water park, "Reservations" should be the next item on your list. You or one of the other leaders should call ahead and inform the company that you will be visiting its facility on a field trip. Be sure to tell the company the type of group that is coming and the number of people. Many places require reservations, and all places appreciate a heads-up, especially if you have a large group.
Securing adequate transportation should be next item on the checklist. If you are taking students on a school bus, make sure to arrange this with your school a few weeks before the trip. Your school will usually contact the drivers for you and have them waiting at the designated time. If you are taking groups of cars, contact parents or other drivers a few weeks before as well. Make sure that there are enough cars (and seatbelts) for each group member and leader.