A modern phone sensor is better than most people need. What separates professional-looking footage from the rest is almost never resolution — it is light on the face, sound close to the mouth, a steady frame, and knowing what you are going to say.
Lock your exposure before you start. Automatic exposure hunts when you move, and that hunting is one of the clearest signals that footage was shot casually. The same goes for white balance, particularly if you are walking between rooms with different lighting.
Get the microphone closer than you think you need to, or use one you can attach. And write the thing down. A script does more for the finished video than any setting in this list.
