Know your goal and state it clearly. Do you want the reader to do something for you or are you merely passing along information? Do you want a response from the reader or do you want him to take action? Your purpose needs to be stated in the communication. Avoid information that is not relevant. Clarity is key.
Tone can help your writing be more effective. Certain forms of communication, like memorandums and proposals need a formal tone. Writing to someone you know well would need a more informal tone. The kind of tone depends on the audience and purpose of the writing.
Explain in clear terms what you want the reader to do. They can not oblige if they do not understand. Also, they may not even want to try to help if the communication is vague and sloppily written. It is good to include why it is beneficial to them to do what you ask or to help you.
Language needs to be simple. Do not overuse clichés, jargon, and expressions or try to impress with big words. Keep sentences and paragraphs short and concise.
Less is more when it comes to length. Leave out words that do not contribute to the main focus of the communication. This can make the reader work harder to know why you wrote.
Using an active voice will strengthen your writing. Sentences that are written in the active voice will flow better and are easier to understand. Long, complicated sentences will slow the reader down, even more so if they are written in the passive voice. An active example is “I caught the ball.” and a passive example is “The ball was caught by me.” Active voice will engage the reader and keep his attention.
Good grammar and punctuation are very important. It is a good idea to have someone else proofread your writing before you send it. If you cannot do that, then try reading it out loud.
Read more at http://grammar.yourdictionary.com/style-and-usage/what-is-effective-writing-communication.html#jR13gS2SMA1wk04p.99
