In over a decade of public speaking experience, the biggest bang for the buck I've ever gotten was about eye contact. First, do it. Second, pick three people in the audience (left, center, right) to do it with. Speak individually to each one, rotating to the next after about a paragraph, cycling as many times as required. While you're speaking to someone, they are your proxy for the audience: if she nods the audience is nodding, if she laughs the audience is laughing, if she looks confused the audience is confused. Adjust as required.
Here's how the audience perceives what you're doing: everyone will think you spent roughly one third of the speech talking to them, specifically, which is enough to be flattering but not enough to be creepy. The constant movement of attention means you keep moving [+] and don't stare at one person for the entire speech. Your audience will come away with a feeling of closeness and emotional rapport because you were "listening" to them during the speech via your proxies.
+ Don't give a speech seated or standing behind a podium/lectern: weak speakers have a tendency to hide, and the body language tends to come across as fidgeting even when it isn't.
Likewise, that's some of the best advice on speaking I've gotten too. I always picked five people - front right, front middle, front left, back mid-left, and back mid-right, and just cycle through them. If you know one of the people personally, all the better - they're more likely to give you a little nod or otherwise encourage.
Definitely move around.
Also, people forget - first and foremost, you've got be entertaining. If you're informing but not entertaining, people will tune out. Energy levels higher than normal. It's hard to have too high energy so long as you're not out of control. It's very easy to have too low of energy. Rarely has a speech been bad because the talker was too enthusiastic (I know there's memorable counterexamples, but they're really truly the exception).
Rarely has a speech been bad because the talker was too enthusiastic (I know there's memorable counterexamples, but they're really truly the exception).
Very few people even have the capacity to cross the line between "enthusiastic" and "Ballmeresque".
It's easier to give a long speech. In Toastmasters contests, the time limit is 7 minutes and 30 seconds. I used to own a couple DVDs of the World Champion of Public Speaking competition. At that highest level, the content, delivery, timing, story, presentation are all super polished and honed to a sharp edge. Yes, they all tend to be a tad too motivational but that's what the best speeches tend to be (and the best speakers aspire to be...).
Here are a couple examples (from the same guy - most of the winning public speakers seem to now professionally coach speakers for a living and don't share their speech videos online):
My biggest speaking advice is to spread your legs a little further than shoulder length. I do not know why, but this simple stance will give you a lot more stability and stop the fidgeting.
Having talked at many conferences there are a bunch things I do:
# Practice, seems simple but when I don't then it will not be as good as when I do.
# Go early and talk to a couple of the people that will be watching the talk. This calms me down as I now have a couple people on myside. It backfired once when I started talking to someone and they turned out to be a jackass, but I moved onto someone else.
# Use the people I talked to as my eye contact, there now friends I should be able to look at them
# Take everything out of my pockets and anything I might start fiddling with off.
# Slide Remote is key as you can interact with audience better.
# Simple slides - one phrase or simple list is usually best, for tech talks I write a snippet on the slide
# Pause and Breathe, it may seem like a long time since the previous word but its not. This tends to be why people start adding filler words (aww, like...)
If you find making eye contact unnerving, look directly at the gap between a person's eyebrows whilst speaking - to them it's indistinguishable from actual eye contact.
Here's how the audience perceives what you're doing: everyone will think you spent roughly one third of the speech talking to them, specifically, which is enough to be flattering but not enough to be creepy. The constant movement of attention means you keep moving [+] and don't stare at one person for the entire speech. Your audience will come away with a feeling of closeness and emotional rapport because you were "listening" to them during the speech via your proxies.
+ Don't give a speech seated or standing behind a podium/lectern: weak speakers have a tendency to hide, and the body language tends to come across as fidgeting even when it isn't.