There are three major ethnicities in Singapore; Chinese, Malay, and Indian.  Greetings tend to differ between the three.

Man greeting Man – The Chinese are comfortable with a light handshake, sometimes accompanied with a touch on the arm.  Malay men will use the handshake and also the salaam accompanied with a slight bow.  Indian men will use the handshake and also the namaste.  Handshakes are the most common form of greeting.  They are usually gentle and not to prolonged.  Many people use a two handed handshake when greeting and departing.

Woman greeting Woman- Chinese women are comfortable with a light handshake or just a slight nod of acknowledgment.  Malay women will use the handshake but many times a simple salaam or bowing of the head will suffice.   Indian women will use the handshake and also the namaste. 

Greetings between Men & Women-   While handshakes are a common form of greeting, many times a simple nod or slight bow will do.  Wait for the women to initiate with all three ethnicities.  The majority of Muslim women and men do not touch in public.