The Vietnamese generally shake hands both when greeting and when saying good-bye. Shake with both hands, and bow your head slightly to show respect. Bow to the elderly who do not extend their hand. Vietnamese women are more inclined to bow their head slightly than to shake hands.
When greeting someone, say “xin chao” (seen chow) + given name + title. The Vietnamese are delighted if a Westerner can properly say “xin chao” (because Vietnamese is a tonal language, “xin chao” can have six different meanings, only one of which is "Hello").