How to Write Effective Emails? Tips and Best Practices

The task of changing the world, as it were, starts with us: "Don't do to others..." 

A good email should have a subject line that summarizes your message

People often scan their inbox by the subject. Make your subject line concise, but complete enough so that your readers can decide whether it's relevant. Never send an email with a blank subject line!

The absolutely worst thing to do: You want to write an important (perhaps even urgent) note to person X. You grab the first email from this person that you located in your inbox. It bears a subject line (if any), which has nothing to do with the message you are about to send. You just hit "Reply" and start clicking away. The subject line might have said "Thanks" and you wrote in the body of the email "I urgently need the July monthly report". Would you jump to open an email, which says "Thanks", when you have 50 other email you haven't opened yet?

Give your reader full context at the start of your message
Start off your messages with enough context to orient your reader. Avoid short, yes/no responses to messages, which may deal with several topics. If there were numbered or bulleted questions/issues, respond to them in the same fashion.

Make action requests clear
If you want things done, say so, clearly. The email should only be addressed "to" the person, whom you wish to act (or will hold accountable). Copy (cc.) those, who must know about it. Summarize action items at the beginning of the message. What? Who? By When? This way everyone can read (and understand) clearly what, if anything, they are expected to do. If there is only one requested action, it's best to write it directly in the Subject line. Often, that could be the entire email.

Edit messages before forwarding
Don't automatically forward any email without editing it. Make it appropriate for the ultimate recipient and make sure it doesn't get the original sender in trouble. Delete all unnecessary history from your forwarded message. Subject lines, which look like this "Fw:Fw:Fw: blahblahblah" loose their relevance.

Further Tips and Suggestions:

• Before sending an email ask yourself, would I mind seeing this on the front page of a newspaper?
• If it's a sensitive issue, work out the problem face to face. Pick up the phone or walk over the person.
• Don't reply to an email in a bad mood or when angry. Count to 10. Then, count to 20.
• Write in clear, plain and grammatically correct English. (In the age of Twitter, this may be too much to ask...wink-wink)
• Take time to write good emails. Fast, reactive email will lose its meaning and/or may offend someone.
• Be concise! Too much information can be a burden for people to read.
• Only send email to the people who need it. Don't send it to 10 other people just because you can. Avoid the CYA habit.
• Email should be brief; longer documents should be attached.