In the interests of space (avoiding monster posts like the previous speechwriting harangue), I've decided to break delivery into two topics, basic and advanced. Many people won't actually need the techniques I'm putting in "advanced," like walking points, because they give most of their presentations from a single place or podium anyway. I discourage that practice, but I also discourage use of Powerpoint and clip art. Let's see how far that gets me.
If writing for speech is all about respecting the constraints of realtime communication, delivery is all about power--and if ever a statement deserved to be qualified, that one does. There's nothing overtly sinister about it: I don't necessarily mean that the speaker is in a position of power (although they may very well be) or fighting against power (equally likely), and I'm not trying to say that the speaker seeks to dominate the audience. But as we'll see, the basics of speech delivery often rely on tricks that either evoke positions of power or are common to those in power. It's not hard to see why: probably 99% of the time, a speaker is trying to project authority and trustworthiness to the audience, in order to effectively communicate the message. Not every delivery lesson is tied to this goal, but many--most?--of them are.
Let's take a few areas of good delivery one at a time:
I kid you not, if there's one thing that I tell everyone coming into the studio, it's that they need to smile. You can hear a smile in a person's voice. The physical change--even one that's completely faked--creates an emotional change. It doesn't just work for smiles, actually. Matching your expression to your subject matter almost always produces a noticeable improvement in delivery, but since most people who go for "profound" end up at "bored," you're best off smiling when in any doubt.
Note: do not smile for most speeches about violence against women, inhuman slum conditions, or starvation. Sometimes it's better to sound bored than "happy to be here." I have learned this from experience.
The other important expressive element on the face is the eye. We attribute a great deal of nonsense to eyes, in my opinion. They are not windows to the soul, but they are extremely important non-verbal communicators, and we have a lot of circuitry built into our heads for interpreting their movement. Much of this has evolved in close conversation, where we look to another person's eyes to read their attention level, their reactions to new information, and (of course) their power relationship with us.
Like many of the power relationships being expressed here, these are culturally-specific, and I wouldn't want you to think otherwise. In most Western cultures, a direct gaze is considered important for being trustworthy, whereas in other cultures it may be challenging or even hostile. You'll note that either way, there is a power gradient being expressed. What I will say about eyes, as well as other non-verbal communication, should be evaluated in a Western cultural environment only and may in fact be counterproductive in an intercultural setting.
With that said, the role of the eyes in public speaking is to establish contact without being overbearing. You need to make each listener feel included in the message, but not intimidate them. In order to make this happen, your eyes should meet directly with everyone in the room at regular intervals. Obviously for very large crowds, you'll just have to look in the direction of a group of people, but the principle still stands. I recommend that you maintain that gaze as if you were speaking directly to the target audience member for the length of a short sentence (or in long sentences, for the length of one of its clauses). Finish the sentence (or clause), and move your eyes smoothly to the a new person in the room as you start the next words. You will need to practice this, but in time it becomes very natural.
Make an invisible line across your chest at around your armpits. Now make another line at your belt or waistline. Look at the space between them--this is where your hands live for gesturing. When they are not actively communicating, they should hang naturally at your sides. These are mostly aesthetic considerations: big gestures or overactive gestures will make you look spastic. Depending on your frame, you may also want to be careful with how far out from your body you move your arms--when I first started speaking, I tended to reach out in a very exaggerated fashion, and it made me look like a scarecrow.
The role of gestures in interpersonal rhetoric should be to accentuate and illustrate points. For example, when using an internal preview (I said that it'd be relevant later!), each point should get a its own location in space, indicated by a gesture that "places" them or indicates them. This helps the audience understand that there are three separate points and mentally associate them with a physical process for better retention. You may also want to associate movements with particularly important points, or to walk the listener through a process.
DO NOT ATTEMPT TO PRECISELY MIME AN ACTION AS PART OF A SPEECH. It never ends well. If you can't do it in words, use a printed visual aid.
Gestures actually play very well into the power dynamic of public speaking. Making small gestures, for example, is a long-standing trait of many tyrannical administrators, since it forces their subordinates to pay attention to the slightest move. You shouldn't go to that extreme, but keeping your body under control with clearly-defined and limited movements is a sign of confidence and authority. Some gestures also signify power in greater or lesser degrees. For example, gesturing upward or toward the body with hands in a cupping motion is like a plea for help. It's considered a weak gesture. Pointing is another weak gesture--it looks accusatory (and a bit like the vaunted finger-guns). Spread fingers come across as conciliatory or defensive.
You're better off with gestures that move down or out, with the hands in a natural, relaxed position (all fingers out, but fairly close together). It's almost like a very mild karate chop. The movement should have a definite end, hold for a second, and then relax back to your sides. Above all, nowhere is it more important to tape yourself than when it comes to gestures. It is hard to explain these kinds of things in text--but when you see yourself making mistakes, you'll cringe and then you'll fix it. Self-recording is the answer for a number of speaking sins, but particularly here. Webcams are cheap. Take advantage of it.
If the most common advice I give to people in the studio is to smile, the second most common is that they need to slow down. Nervous people speak faster, and they won't even notice. They may even feel like they're dragging through the text, because the adrenaline in their system has them hopped up so much.
So you probably need to slow down. Technically, you should be speaking at about 120 words per minute, which is easy enough to test: grab a random 120 words from a newspaper or magazine article, stand up in front of some friends, and time how long it takes to read from start to finish. Speaking slowly accomplishes a couple of purposes. First, it ensures that the audience can follow you easily. Second, it's another sign of your authority: high-status individuals are allowed to manipulate the time of lower-status individuals, which is why VIPs are often notoriously late or dismissive of schedules. Take your time and claim that credibility from the room.
Now there are many vocal styles for public speaking. They not only vary from person to person, but from venue to venue. Jesse Jackson's oratory-from-the-pulpit approach stands in sharp contrast to Bill Clinton's one-on-one lovefest, but both are capable of adjusting to a wide range of situations and audiences. They are making a connection with the audience. I would propose that the easiest way for most people to make that connection is to speak to an audience the same way that you would speak to a single person. Make it conversational.
If you've been practicing your eye contact, you may find that this comes naturally. Each sentence should not only be directed with a smile and a direct gaze to that person, but you should talk to that person. Live the sentence as you speak it, as if it wasn't written hours or days before, but as if it's something that you really want that individual to know, between friends. Because to be honest, isn't that the point? You want your message to get out. You want the audience to trust you. So speak to them as your friends, not as if you're the great speaker and they are a passive listening body. Keep it conversational.
Still to come
Good thing I split it up: Pico says I'm up to 175 lines already here. Here's what I'd like to talk about next time: using the physical space of a room, memorizing speeches, and speaking on camera. In the interests of conversation, feel free to ask questions and debate points in the comments for this post, and I'll do my best to respond.