One key difference between professional and amateur writers — and speakers — is how they handle the use of descriptive words. Most amateurs do not use words that are descriptive enough — they might say that a woman wore a provocative outfit, without indicating it was a short dress of a certain color or even a dress at all.
On the other hand, those who begin to understand the need to describe more precisely often go overboard and relate every possible detail of someone's attire to the point that it distracts from the flow of the narrative.
Another important way to give a speech sparkle is to use the active voice, in which the subject takes an action. Instead of the passive “the boy was bitten by the dog,” you would say “the dog bit the boy.” Active is usually more concise and often clearer in meaning and easier to remember.
Use imagery that appeals to any of the senses, which helps make the idea more real and lodges it more effectively in the memory. You might refer to “the laughter as the family passed around the Thanksgiving dishes of turkey, stuffing, and sweet potato.”
Be as concrete as possible, which will enable listeners to instantly see what you mean, instead of having to translate the word into an image. Describe someone going to Kmart, instead of a department store.
Highly successful Republican pollster Frank Luntz, in Words That Work: It's Not What You Say, It's What People Hear, provides a formula for power persuasion: small words, short sentences, be consistent and credible, speak to people's aspirations, provide context and explain relevance, and use visual imagery.
Use dramatic words, like wild, unusual, powerful, enormous, horrendous, evil, devastated, immediately, and extraordinary. These prod the audience to pay more attention to what you are describing. Use the strongest action verb possible — “he ran to the mailbox,” instead of “he went”; “she screamed,” instead of “raised her voice.”