Because it's hard to have fun if you're scared or hurt...
Choose clothing appropriate for the weather and activity you have planned and bring enough water. Occasionally water fountains and restrooms may not work.
Check for ticks, as Lyme disease can occur in this area. Consider wearing long pants and using insect repellent.
Poison ivy is found throughout the park. Learn to identify and avoid it.
Give wildlife plenty of room. How much room is enough? You should be able to observe animals from far enough away that they do not change their behavior because of you. There are snakes on the island, but none are poisonous.