Latin America: If you're headed to Latin America, get ready for some kissing. Standard practice is for men and women to greet women with a cheek kiss to the left. Men usually greet other men with a handshake.
Asia: The most common practice is probably a small bow of the head with hands pressed together and placed in front of the chest.
China: In China, there's a little bit of bowing and then hand shaking. If you're close, you might hold both hands. Do not make eye contact, and execute the handshake lightly and with constant shaking.
Philippines: In the Philippines, younger people bow slightly and then place the right hand of their elder on their forehead. There might also be a pat on the shoulder for good measure.
Cambodia: It might be OK in Kenya and Tanzania, but do not touch anyone's head in Cambodia. That's really disrespectful.
Zambia: Zambians might include a thumb squeeze when saying hello.