Firstly, you will need a valid passport. Most countries require that your passport is valid for at least 6 months after your planned return.
Secondly, you will most likely need a visa – in some cases, this is a simple e-visa or visa-on-arrival; in others, you may need to apply in advance, which will require the correct paperwork. A cost may be involved in any visa application.
There is a lot of other paperwork that may be required, depending on your individual circumstances, for example if you are travelling with children, you will need their unabridged birth certificate, or your destination or transit country may require specific vaccinations.
We strongly recommend that you always check the passport and visa requirements of your destination countries (and any through which you will transit en route) before planning your trip or, alternatively, ask your travel agent to assist you.