There are two key parts to creating a good video—good audio and a good visual. Low quality audio is often much worse than a bad visual.
For good audio:
Speak up in a quiet room. This will make sure that the white noise is not normalized with your voice.
Use the microphone on your earbuds instead of the one in your computer or phone. This allows the microphone closer to your mouth and create a better recording of your voice.
For good video:
Do your best to keep the recording device steady whether it is on a tripod or just resting on a desk.
If you are using a smartphone to record your video take a horizontal video.
Try to keep the microphone hidden from the camera.
Some information for this section was gathered from this video.