Arrive well before your video conference starts to test the videoconferencing system and the interface to your laptop.

Do an audio check before the virtual meeting begins to ensure that everyone can hear you.

Speak in a normal voice, you shouldn't have to shout.

Talk directly into the microphone. Do not turn your head from side to side while talking or your voice will fade in and out at the remote site.

When possible, keep your microphone muted when you won't be speaking for several minutes or more. Un-muted microphones can be the single most important problem communicating during a videoconference meeting.

Be natural, but limit excess movement to avoid looking jerky on screen. If you walk around while speaking, remain in a small area and walk slowly.

Minimize distracting glare and uneven lighting by pulling the shades on windows and doors and covering glass-framed wall hangings.  You should minimize combining outside light with indoor fluorescent lighting to prevent problems with the videoconference camera and the quality of your image.

Make sure the room has adequate lighting, typically what would be used for standard office work. If it's too dark, the other sites won't be able to see you clearly.

Try to set up a back channel for communication to the other site(s) such as with Instant Message client or email.  This allows for communication without interrupting the discussion.

Wear neutral, muted, or pastel solid colors. Avoid plaids, stripes, polka dots, very bright colors, and the colors white or red—they can cause distracting effects on screen.