The most common piece of advice from the speech coaches of the world, and one of the most unobjectionable, is "make eye contact."

Is there any more to it than that? 

Some folks advise looking over the heads of the crowd, into space, as a way of coping with nervousness.  This is very bad advice, on two levels.  First of all, the crowd knows you’re not looking at them, which translates into "not interested."  We look at things we’re interested in — it is that simple.  So look at the audience.  Second, it doesn’t get you over your nervousness, because the audience remains mysterious.  If you look at one person in the crowd, and then another, you’ll gradually realize that it’s just a collection of individuals — and you have no problem talking to individuals, right?

So you need to look into the eyes of the audience.  How do you do that?  How long do you look?  If you’re falling in love, then forever isn’t long enough.  For any other kind of moment, don’t dart around with your eyes, because that telegraphs nervousness and insincerity.  Look at people as if you were talking to them — up to thirty seconds if you’re expecting a response, or getting a response or even hoping for a response.  Just as you would in normal conversation, keeping in mind that there are a thousand other people in the audience who want attention too.

Finally, give some thought to how your eyes look.  If you’re nearsighted, for example, but not wearing your glasses for reasons of vanity, then beware the squint.  If there are bright lights shining on you, also beware the squint.  Narrowed eyes indicate suspicion, and your audience won’t like that much.  Try to keep your eyes open.  Michael Caine, the famous actor, trained himself early in his career not to blink when the camera was on him.  He figured that his eyes were forty feet across in close up (on the big screen) and blinking was like turning the lights out.  We tend to blink rapidly when we’re nervous, and Caine quickly got a reputation for cool which may have something to do with his not blinking at all. 

To make good eye contact, look at individuals as if you were talking to them in conversation, and keep your eyes open.  Think Michael Caine.