The Wai is the common from of greeting and adheres to strict rules of protocol,Raising both hands,palms joined with the fingers pointing upwards as if in prayer lightly touching the body somewhere between the chest and the forehead,is the standard form.
The wai is both a sign of respect as well as a greeting respect and courtesy are demonstrated by height at which the hands are held and hoe low the head comes down the thumbs of both hands.