Out of politeness, always ask permission before taking photos of people and places of worship. Remove your shoes before entering Buddhist pagodas. You may place small donations in boxes found in the temples, as this helps pay for their upkeep.
A gentle handshake and a smile is the most appropriate manner of greeting. Be firm yet diplomatic when dealing with officials who can be rigid. In case of a misunderstanding, patience and good humour is the best policy.
Small gifts such as foreign cigarettes, lighters, pens, liquor and perfume are generally appreciated by people you may befriend or who assist you.
If you are spotted giving money to street beggars, especially in Ho Chi Minh City, you may be mobbed by others. A donation to a reputable charity is considered a better alternative.