The principles in this book, summed here by @ameet are really great.
It comes down to three simple things that are very hard to do sometimes because writing has so many variables.
1. Begin with the answer.
2. Appropriately group and summarize the supporting points.
3. Apply logical order.
These are important because of how our brains work…particularly when people are very busy (like everyone today).
It really is important to provide an up-front “why should I care? attention getter and keep the mind engaged without confusion.