Here are two principles to follow to make your writing powerful.
Singleness of purpose
Write with a single purpose. That way you’ll not overwhelm your reader with too much information and you’ll be clear and persuasive. Everything in your document should be essentially about one idea. This is called unity.
Deal with one idea at a time. Each sentence, paragraph, chart, heading and section should deal with one subject. They should all be leading the reader to understand the overall purpose of your document, which should also be about one idea.
So if you’re sending an email or writing a short blog article, make it about one thing (or possibly two things grouped as one, sometimes!). It’s the same if you’re writing a lengthy report—make sure the reader is clear about what it’s about, and what they should do.
Coherent writing means the relationships between ideas are clear. Each idea should relate to the others, with one idea flowing smoothly to the next. Each sentence should have some link to the previous one. Move from the known to the unknown. Use transitions to show the logic between them.
The first sentence of your paragraph should be a topic sentence. This sets the scene, and the following sentences should provide supporting examples, expansion and explanation of your ideas.
Hit the reader with the most important information first. This applies to both paragraphs and your document as a whole. Think like a journalist and use the inverted pyramid:
Highlight the first sentence of each paragraph of your document. If you ignore everything not highlighted and it still makes sense, it shows your ideas are logical and coherent.