Footwear - Most important! Sturdy hiking boots or sneakers with a stiff sole and pronounced tread. The roads and trails are rocky, and there may be mud and snow even on the climbs in summer.
Backpack - A small, comfortable backpack for carrying water, food, sunscreen, a first aid kit, and personal items.
Cash - For park entrance fees, small purchases from locals (if encountered), or for jeep hire for the descent.
Additional (recommended):
Flashlight or headlamp (if you plan to stay until dark).
Power bank for charging devices (service may not always be available).
Small first aid kit (bandages, painkillers, antiseptic).