Conciseness
Conciseness means saying things in the fewest possible words. To achieve this, try to avoid wordiness or redundancy.
商场如战场，人们都不愿意用太多的时间去读冗长的信，而简洁扼要又不失礼貌、清楚是最受欢迎的。

Concreteness
Concreteness means making the message specific, definite and vivid.
该具体时就不要笼统含糊，应该让读信人得到准确的信息，但要灵活掌握。做生意贵在争取时间，询问不具体，必然导致收信人的进一步询问使自己贻误时机。