Only use a direct quote when it is more succinct than you would be yourself. 2-3 lines max. Synopsize longer quotations. This is one area where speaking and writing differ. When you're speaking, you only have one shot at it. If one is reading a paper and the quotation doesn't make sense, one can re-read it.
Paint the audience a picture . . . in Technicolor!
How big is a debt of $4 Trillion? So what? How much is that? The human mind cannot even really conceive of such a number. You could string together a bunch of zeros on the board for impact, but, even then, it has little impact on your auditors. Here's an illustration: If you began at the time of Christ, and spent $125, 000/hr., 24 hrs./day, seven days a week, month after month, year after year, you would have spent $4 Trillion sometime around 1990. Now THAT has impact (especially if you pause a little after each clause)!
The Great Wall of China is 1, 500 miles long. So what? How long is that? It is one of the only man-made structures visible from space with the naked eye. It was made by manual labor, and is about as high as the (choose a landmark or building visible from wherever you are--it's important that the audience sees a structure with which to compare the Wall) and strectches all the way from Omaha (pause) to Seattle (gesture with your outstretched hand to emphasize the distance).
Don't simply ramble on with endless data. Don't spew factoids. Learn to compose fully developed lines of argument.
Focus on the essential points, then elaborate through examples, analogies, illustrations, etc. Say you're giving a speech about a vacation you took. If you try to tell everything you did and saw, in a 5 minute speech, it would probably be very superficial; paint a rather flat picture. But, if you focus on your favorite site, and elaborate on three things you liked most about that--painting a vivid mental image--they'll probably even get a little excited about going there themselves someday!
This applies especially to statistical evidence. Don't expect statistics to speak for themselves. Have you ever gotten the comment, in the margin of a paper you wrote to the effect that, "I don't see the link between what you said up there and the point you make here?" That's probably because, at the time you wrote it, the link was abundantly clear in your own mind. Right! You've done the research. You've put the thought into it, and, by the time you write, or speak, on the topic, to state that link would seem like stating the obvious. The only thing is, it's not so obvious to your auditors, so go ahead and spell it out for them.
A good speaker knows how to apply the information in a way which enhances the argument. Where's the impact of this point? Why are the numbers I'm quoting here significant? Explain the implications of what you are telling me--in other words, make the connection, don't assume the audience will follow you.
Dead speeches are BORING! So make your speeches lively!