Consideration
Prepare every message with the reader in mind attitude and try to put yourself into his/her place.
设身处地的为读信人着想，并把可能出现的问题都考虑进去。

Courtesy
It is not mere politeness. The courteous writer should be sincere and tactful, thoughtful and appreciative.
礼貌是商场上的锐利武器之一，写信而不注意礼貌，犹如打仗时没有子弹。俗话说“礼多人不怪”，恰当地运用礼貌词语并不影响行文的简洁，而且有助于赢得读信人的好感；及时回信也是礼貌的表现，反之无故拖延是不礼貌的表现。

Clarity
The writer must try to express himself clearly so that the reader will understand. To achieve this, he/she should keep in mind the purpose of his/her letter and use appropriate words in correct sentence structure and convey his/her meaning.
语言表达清楚，避免读信人产生误解。牢记写信宗旨，根据已确定的目的，运用恰如其分的词语、正确的时态和结构来表达。打字、手写也要清楚、美观、整洁。