Writing originated as a means of recording and transmitting speech.
The essentials of good presentation are similar for speaking and writing.
If you are presenting a subject to an audience, whether in speech or in writing, you will be better understood and remembered if you tell them what you want them to know three times, like this:
- Tell them what you're going to tell them.
- Tell them.
- Tell them you've told them.
The first and last should be as brief as possible. The detailed explanation is all in the middle part.
Why tell them three times? Because it is easier to learn something that is repeated. Some people have photographic memories, but most people don't. It also allows anyone who hasn't quite caught the idea the first time round to check that they have understood it. More than three times is unnecessary repetition.
Similarly, any extended piece of writing, such as a report, should start with a summary that shows the reader what to expect, as briefly as possible. For example, a 60-page report should begin with an executive summary of one or two pages summarizing major points.
The body of the report will contain a careful explanation of what you are communicating, supported by references in footnotes or endnotes.
You will then end with a conclusion that summarizes not only the main points, where relevant, but focuses on any recommendations for action that flow from them.