In this essay, first published in 1946, George Orwell laid out his six rules for writing. Note how they apply not just to writing, but to all forms of communication.
Think about all of the books/articles/speeches/presentations/conversations (especially conversations!) that would be drastically improved if everybody kept these six points in mind:
1. Never use a metaphor, simile, or other figure of speech which you are used to seeing in print.
2. Never use a long word where a short one will do.
3. If it is possible to cut a word out, always cut it out.
4. Never use the passive where you can use the active.
5. Never use a foreign phrase, a scientific word, or a jargon word if you can think of an everyday English equivalent.
6. Break any of these rules sooner than say anything outright barbarous.