Man greeting Man – A handshake is the norm usually with both hands (the hand sandwich) and a warm smile.   

Woman greeting Woman - A handshake usually with both hands or a slight nod of acknowledgment will do.  Sometimes women will kiss each other on the cheek if they know someone well.  Light hugs are common for good friends and family.

Man greeting Woman - A handshake will do.   It's best to let the woman initiate.  Sometimes people will kiss each other on the cheek if they know someone well.  Light hugs are common for good friends and family.

Note: It is taboo for religiously observant men to touch women and vice-versa.