Place the information in categories relating to various aspects of your topic.
From there, sort the information into level of importance from most important to least important in being able to communicate about your topic.
You then can determine what would actually contribute to presenting your topic clearly and what would be extra information that could add some value.
Then determine what information would subtract value from your subject or fall into rambling about the subject.
Next, begin to gather the main points of your topic by putting them in order of what the reader needs to know first and then continue to what they would need or want to know last.
You will be introducing your topic, giving information about your topic and then explaining to your reader or listener why this information would be of value for them to know.
Sort the main points into an outline.
When you have the major part of the outline in place begin to add to those main points just enough extra information to increase the descriptions and give value to the topic so your reader or listener would feel like it was helpful additional information to understand the topic.
Write down your information and add just enough to keep it interesting and maybe, at that point, just a few extra tidbits that would add but were not really necessary.
This way you will be staying on topic and the reader or listener will be able to determine if they want to find out more about the topic you have presented to them.
If you just stay with the main facts with limited extra information the reader or listener will value your presentation more and can then easily determine if getting more information would work for them.
They will appreciate your ability to present information and stay on topic.
It shows respect for their time and that places you as a writer or speaker higher on their list to come back to you for information in the future.