Man greeting Man - Men usually shake hands when greeting one.  At a first meeting a handshake will suffice and is sometimes combined with slight touches on the arms and/or elbows.  Good friends will usually hug.

Woman greeting Woman - At a first meeting, a light handshake will suffice.  Some women will hold onto to forearms rather than hands.  Friends and close acquaintances generally kiss each other once on the cheek while lightly holding both hands.  

Man greeting Woman -  At a first meeting a regular handshake will do.  Friends, family and close acquaintances will share a light kiss on the cheek.