Passport and other documents
Travel insurance
Credit card, debit card, pre paid card or whatever you use for paying
Flight and hotel details
Clothes for a beach holiday, tops, shorts, swimwear, towel, something for the evening, long trousers and top plus good shoes if you plan excursions (if you go anywhere on the jungle shorts are evil), sport wear if you are a gym person and the hotel has facilities, underwear and nightwear
Suncream, insect repellent
Medication like plaster, antibiotic cream, pain killers, thermometer, insect bite cream
Toiletries
Small tube of washing detergent
All chargers you need for electronics
Books or other form of entertainment
Camera