The Headington Rules for Speechwriting

Generally speaking, speechwriting is two-thirds research and one-third actually writing.  But there are a number of techniques anyone can use to make a good speech great or a mediocre speech better.  I had the good fortune to be trained under Mark Siegel of Mark Siegel and Associates (also former Executive Director of the Democratic National Committee and speechwriter for Senator Ted Kennedy and Pakastani Prime Minister Benazir Bhutto).  Below is an aggregation of his ideas, Ted Sorenson's and William Safire's.

1. Great speeches communicate great ideas.
2. There should be a shapliness to your speech (beginning, middle and end).
3. Good speechwriters use an outline to ensure shapliness.
4. Use a handshake (icebreaker) to warm the room and relax the audience.
5. A speech should be made for a good reason and have a purpose.
6. Use rhetorical antithesis ("Ask not what your country can do for you, ask what you can do for your country.") to provide a speech with quotable phrases and rhetorical nuggets.
7. Use enthymede (a syllogism/rhetorical device) to make a point without saying it.
8. Use anaphora (repeated beginning, repeated ending) to avoid monotony and also to reinforce key themes in a way that draws the audience into participating.
9. A speech must fit the occasion and not be separated from purpose (i.e., State of the Union speech versus a eulogy or Congressional floor speech.
10. Use imagery to freshen and animate a speech.
11. A great speech is a function of timing; build the speech, like a wave cresting.
12. Length is important.  Chose each word as a precision tool.  Most good speeches do not exceed 20 minutes.
13. The forum is the place of speechifying and relevant to the content, writing and delivery of a speech.
14. Know your audience (who you're trying to influence).
15. Use similes, alliteration, and metaphors for rhetorical phrasemaking and turn an ordinary speech into a beautiful one.
16. Use triplets (rhythmic triads/grouping words into patterns of three) to cause a memorable effect (i.e., "Veni, vidi, vici," "the kingdom and the power and the glory").
17. Use quotations to bring in references and history and use the language of others with whom you share values and ideas.
18. There is only one speechwriter.  Many people can contribute to its development but only one person can write the speech--unless you're willing to sacrifice thematic and structural coherence.
19. Use an elevated tone and avoid slang, tired cliches and trite language.
20. Remember the speechgiver.  Use words they are comfortable worth and try to write in their voice.
21. Delivery is the final step in eloquence.  Spend time and play with the rhythm and cadence, always remembering that television is a cool medium and hot rhetoric is best left off-camera.
22. Peroration (the end of the speech) is what is most likely to be remembered so be sure to make it memorable.