Luggage and bags:
A suitcase or a backpack (more easy when travelling on the road by motor / bike).
Clothing/Shoes/Weather Gear: In summer the weather can be quite agreable. You can put summerclothes on, but the weather can change very suddenly (as in any place in the Netherlands) so always bring a light coat with you. In spring and autumn it can be chilly and rainy. So put on that long pair of trousers and bring your coat and umbrella with you! In winter it can be quite cold. You need a warm coat, maybe a pair of boots , a sjawl and mits (mittens?).
Photo Equipment: Take your camera with you. You can buy film and get your pictures developped here if you want.
Luggage and bags: Binoculars, camera, long lens and lots of film. You are going to see lots of monkeys.