Please feel feel free to add pictures and comments.

A framing that works well. Head in top third, hands at bottom, subject speaking to the camera.
Bad angle.

Poor camera placement - too far above, too far away. You lose your audience quickly if they can't see the subjects face.

Too dark, bad angle. Even when the lighting looks good to the naked eye, the camera may see differently. We were able to correct lighting problems by using a couple of lighting adjustment settings in the camera; "backlight" and "cloudy sky", and moving the camera to the other side of the sanctuary.

A first-time video with two problems: The aspect ratio is wrong and there is strong backlight which makes the subject appear dark. The aspect ratio problem is from a video taped in widescreen 16:9 which was then processed and uploaded in 4:3. This makes the subject look "skinny". Backlight issues are a very common problem because the camera sees things differently than our eyes do. In this case the problem would have been diminished using a backlight function or "blc" button on the camera.

An evening recording with no natural light. When light is decreased, so is the color range. Focusing can be compromised as well. If possible, include as much natural light as possible. If that isn't an option use strong indoor lighting and compensate with settings in the camera.

Objects between the camera and the subject can become inadvertent focal points for your camera's autofocus. This is a microphone left in place after a children's choir performance.