The following recommendations will maximize the quality of the video call.
The end results of a webcast production is directly dependent on the quality of the incoming video/audio from the remote site.

Environment

Choose a quiet place, preferably closed room (controlled environment)
Ensure all other programs/applications that may interfere with the video-call are closed/silenced
Usage of a wired network connection is strongly recommended.
It is recommended to test from the location where you will conduct the video-call for the actual event and in the similar conditions (time of day, hardware used, etc.)
If placing the call from a home office, keep in mind all other home internet activity will affect the bandwidth available for your call. (Example: Netflix, Video streaming, Audio streaming devices, Web browsing(social media) and Wifi enable applications will be using the same internet bandwidth.)
Virtual Meeting Room Connectivity Test

Sound

We strongly recommend using a headset microphone. This ensures the same distance between the sound source (the mouth) and the microphone at all times during the call.
Place under the mouth, at 2-3 cm (see pic. above)
Make sure that no sensitive part of the mic comes in contact with your face or clothes

Web Camera Placement

Webcam

Adjust the webcam at eye-level
Adjust the frame:
- The eyes must be placed at about the intersection of top and middle third of the image
- Horizontally center the face

Lighting

Light source must come from top and front
Use a large surface light source (window better than desk lamp)
If possible, always try to be forward facing a window (daylight)
Avoid mixing daylight and artificial light
If your event is longer than 1hr, keep in mind the changes of the daylight throughout the day, ensure you can control the direct sunlight (Blinds) if this becomes a issue.

Background

Solid or with few details (avoid busy backgrounds)
Fixed (no movement)
Keep in mind the webcast interface for your participants/viewers already contain logos, so additional branding in the background is not required.

Standing up speaker (conference room)

Respect traditional shots sizes
Prefer a medium shot
If the speaker is supposed to move, make sure that the shot is covering his potential positions