We recommend at least to bring the following list of essential things:

Long sleeved cotton t-shirts
Insect repellent
Long trousers
Zip-lock bags
Shorts 2 or more
Flashlight with extra batteries
Cotton socks,  one pair per day
Sun block
Comfortable walking shoes and sandals
Insect repellent
Windbreaker or sweater,
First aid kit
Toiletries (biodegradable shampoo and soap)
Hat or cap
Bathing suit
Water bottle
Underwear, one per day
Sunglasses
Camera with film speed 200 or 400
Small backpack  of 20 liters