For travel in many South American and African countries you will also need an international Certificate of Vaccination card proving that you have the required vaccinations (eg yellow fever). While you might be able to get the shots at the border it is much easier (and possibly safer) to get them at home before you travel.
I would also recommend keeping a list of your credit and debit cards together with the phone numbers to call in case you lose them.
In some countries (eg Argentina) you will want to keep proof of purchase of local currency so that you will be allowed to exchange any remaining pesos back to dollars when you leave.