Always be punctual and call ahead if you are running late.
Remember your mobile manners. Make sure that your phone is on silent. Smartphones should also be ignored unless a message is urgent or relevant to the meeting. Never send a text mesage or repeatedly check your phone during a meeting.
If you are the host, check that everyone is settled and comfortable before you begin. Introduce everyone to each other; a handshake is usual for the office. Social kissing should be saved for very close or longstanding clients and colleagues. Business cards should be exchanged at the beginning of the meeting.
Take some brief notes - it will cast a good impression. Participate and engage in the discussion but don't monopolise the meeting.
Be interested in and responsive to presentations.
Never be argumentative, confrontational or rude. Avoid swearing or controversial topics of conversation. Never contradict or question a colleague in front of clients.
Never yawn and don't hog all the biscuits...