Reply from Agony Uncle
In Singapore the immigration is very efficient and even when there is a queue one should be out rather fast as the queue moves quickly.
-However in other countries queue as well as waiting time is long and one is expected to spend a considerable period of time waiting.
-First rule of course you have to queue that goes without saying.
-Secondly refrain from coming into physical contact with the person queuing in front or behind you unless you are travelling together. Do mind your luggage so that they do not accidentally hit the person next to you.
-Refrain from chatting loudly whilst in the queue. In some countries this is prohibited together with the taking of pictures and the answering of phone.
-Unnecessary violating the rules might ruin your trap bait for business or others.