Backlit Video Subjects
One of the enemies of all video cameras, but more especially phone cameras and webcams, is backlight.
When the subject you are shooting (which may be you!) is between the camera and a strong light source, then alarm bells should sound. The light source doesn’t actually have to be inherently strong (like the sun or a table lamp), it just has to be the strongest light source in the area, for there to be a problem.
If you don’t have any control over the light in the environment, what you need to control is the position of the subject and the camera. If you are shooting a webcam video, for example, then you are much better off facing a window with the webcam looking at you, than with your back to the window.
If the light is very strong, of course, then you will need to beware of shadows. This is apparent even on TV news when the reporter is looking into direct sunlight but the shadow of the cameraman can be seen on the ground nearby. Avoiding shadows is one of the great challenges of professional film and video production.
Not only does backlight throw the subject initially into shadow, it will cause a camera (running on automatic settings) to try and compensate. Often this means that image quality drops noticeably. It can also cause focus issues if the image simply isn’t bright enough.
Remember the maxim that if you can’t control the position and brightness of the light, make sure that the brightest light is roughly shining into the back of the camera, not the lens at the front.
If you avoid backlit video subjects you’ll look a lot more flattering, and professional into the bargain.