Check in advance what identity documents are required when traveling to a given country. To do this, visit the website of your country's Ministry of Foreign Affairs. A valid ID card or passport may not be sufficient. Some countries require the document to be valid on arrival, while others may require it to be valid e.g. min. 150 days from the date of arrival, or for the entire stay. Also, always have a printout of your flight booking with you. Usually you won't need it, but there are times when it may come in handy. Also remember about the identity documents for the child. Each passenger must have their own ID, even an infant. If you do not have the required documents, you may be refused a flight, and in such a situation you are not entitled to a refund. Remember that a photo of an ID card is not enough, just like a driving license ;)