This tip is mainly for those headed to South Africa: make sure there are at least two blank visa pages in your passport, because it is required by South African immigration officials. If you arrive in the country with out at least two blank pages, they can and will deny you entry to the country, and put you on the next plane back to where you came from.
From the U.S. Department of State website’s South Africa information page: “Passports must have at least two fully blank unused, visa pages upon entry for endorsing visas, permanent residence permits, and entry/departure stamps.”
Most departure airports now ensure that passengers have the required blank pages before ever setting foot on the plane, thus ensuring there are no unhappy surprises upon entering South Africa.