The standard Lao greeting is, “Sabaideebor” which means “how are you?” or “are you well?” This is usually done with both hands pressed together in a prayer in front of your body and accompanied with a slight bow or nod. The response for “sabaideebor” is usually “sabaidee”. Some men will also use a standard handshake. These tend to be on light side. Always smile during greetings.

Source: http://factsanddetails.com/southeast-asia/Laos/sub5_3b/entry-2952.html