FORTUNE — What with teleconferencing, Skype, and global conference calls, technology has wrought a sea change in the way people hold meetings. That can be great, not least because it saves some big companies millions annually in travel costs. The downside: Coming across effectively in a virtual gathering is tricky.

“Most executives today ‘grew up’ with in-person meetings where everyone was seated around a table in the same room,” says Scott Weiss, CEO of communication consulting firm Speakeasy. “So a virtual meeting is a strange environment, partly because you usually don’t get immediate feedback to let you know how you did.”

Small wonder, then, that although 67% of senior managers in a new Speakeasy poll expect more virtual confabs in 2012, 62% say they’re concerned about their own skill at making the most of these meetings.

The risks in blowing it are real, Weiss notes. “Let’s say you have a regularly-scheduled quarterly strategy meeting with all of your senior people in various locations, and you decide to do it as a teleconference,” he says. “If everyone doesn’t get everything that’s being said, or someone doesn’t have a chance to contribute vital information, you might not realize it until much later — after substantial damage has been done to the business.” Gulp.

Weiss and his team have coached executives at Fortune 500 companies like Coca-Cola (KO), Microsoft (MSFT), Home Depot, UPS (UPS), and General Motors (GM) on how to avoid that. A few pointers:

Minimize visual distractions

Obviously, in a phone meeting this doesn’t matter, but in a teleconference where your audience can see you, “dress as you would for a television appearance,” Weiss suggests. That means conservative, simple clothing, like a dark suit and solid-color shirt or blouse. Avoid white, since it can create a glare under the lights, and busy patterns like houndstooth.

Keep your eyes on the camera lens

This is usually a small black dot, and it feels strange to stare at that when your impulse is probably to watch the monitor instead. “The lens is your means of eye contact. Looking anywhere else comes across as evasive or inattentive,” Weiss says. “It also looks rude, like looking over someone’s shoulder when you’re talking to them at a party.

“Even in a two-hour teleconference, you have to stay focused on that lens. You don’t want the camera to find you looking down at your cell phone, for example,” Weiss says. “People often tell me they’re exhausted at the end of a long virtual meeting from being ‘on’ the whole time.”

Try to stand while you’re speaking

If you must sit down, compensate for the dampening effect on your voice by sitting up straight, with your feet flat on the floor, and breathing deeply.

“The camera and microphones exaggerate everything,” Weiss adds. So maintain a more formal posture than you would in person and “don’t slouch.”

Speak slowly. Pause between ideas

“In person, many executives tend to speak rapidly,” Weiss notes. “But in a conference call or teleconference, it’s crucial to give people time to absorb what you’re saying — especially since, if you can’t see them, they may be multitasking while you’re talking.” Leaving a pause between the points you want to make gives listeners a chance to comment or ask a question, which leads to the next tip:

Keep it collaborative

“Too many virtual meetings are data dumps, where one person dominates the discussion — usually the highest-ranking person,” Weiss says. “It’s frustrating for everyone else, and it’s dangerous, because if you give people no opportunity to comment, you really have no idea whether they understand you or not.”

One way to make sure everyone has a chance to speak up is to appoint a host or moderator who will chime in and ask attendees for their views. (This also has the salutary side effect of discouraging too much multitasking: No one wants to be noticeably not paying attention when called on for a comment.)

The biggest reason not to hog the limelight, Weiss says, is that “many deep thinkers are not assertive enough to just jump into the discussion. Someone may have the answer to a problem you’re trying to solve but, by not pausing enough and not asking for input, you miss it.”

In that respect, at least, virtual meetings are no different from the in-person kind.