Empathy. When a person relates to the message. When a reader feels in touch with a persona. When a writer has accurately penned thought and emotion into type and script. How is this accomplished effectively through mere words and phrases?
Flow. It is important to maintain fluency throughout the article; disjoint sentences and paragraphs will quickly close the mind and hinder understanding. Start with a topic that interests your readers. Lead them through related concepts, each laying down a foundation for the next. Establishing a smooth flow is essential to keeping your readers focused, but there is more than just eloquence that brings a note to life.
Variety. Exercise a combination of short and long sentences to achieve "sound bites" - phrases that resonate in the reader's mind. Avoid using a term multiple times if possible - this can create distractions and break fluidity of the text. Different terms with synonymous meanings juxtaposed is a pleasure to read.
Impact. The memorability of a piece of writing can be enhanced through writing techniques. Switch between active and passive voice. Break the rules. Use repetition intentionally for effect. Repeat a word when its definition superceeds the meaning of the full sentence. Repeat a sentence when it makes a crucial point. Never repeat a paragraph.
Revise. Step back and take in your work with fresh eyes. What is the topic? Does it flow? Is it coherent? Will it be remembered? Can it be improved? How does it end? Ask these questions as you revisit and refine your composition.
Conclude. Whether it be a cliffhanger, a twist, or a resolution, conclude. Leave your readers with the feeling of satisfaction of a good read, and inspiration to try something new. As always, practice makes perfect.