READ FIRST - safety
Crime is high in some places in Papua New Guinea, and parts of the Highlands see tribal conflict. A high degree of caution is advised by many governments. Just before departure, read your own government's travel advice. In other cities as well as Port Moresby, never walk on your own outside hotels, avoid travelling at night and rely on transport arranged by your hotel or operator. Also keep the contact details for your own embassy, or for whichever country represents yours.
Entry
Which visa rules apply is set by your passport, so consult the official immigration authority (ICA) prior to booking. Sources mention a visa for tourists granted at the main airports on arrival, as well as an e-Visa requested online beforehand, though they disagree on details; applying early for the e-Visa gives more certainty. The usual documents are a return ticket, hotel details, proof of funds and a passport that remains valid for 6 months. A doctor can advise on malaria prevention. Overland entry from Indonesian Papua follows separate rules, so check with both immigration offices first.
Culture and travel - take note
More than 800 languages are spoken in PNG, where customary land ownership is a strong tradition. Always get permission before going into a village or photographing it, and respect local customs. Wear modest clothing. Festivals like the 'sing-sing' are colourful, yet a reputable operator should be used for visiting them. Betel nut chewing is widespread, and red stains on the ground should not be mistaken for blood. Flying domestically is the main means of getting around, and flights often run late, so leave spare days in the schedule. A licensed guide and a permit are required for the Kokoda Track. Do not drink the tap water. Halal choices are limited.