Welcome - a kiss or embrace from a stranger is insulting and humiliating. Traditionally, Lao people use the 'NOP' on meeting and using it will win you instant friends if performed sincerely.
How to use the 'NOP'?
Raise your hands in a praying gesture. The higher you go, the more respect you show, but don't be over the top!
A handshake will suffice, but try to use the Lao greeting of 'Sabai Dee'.