If possible, film each shot a few times just in case there is a problem. How loud are passersby? Is there traffic? We tend to block out these everyday noises in our normal life, but you will be surprised how loud and obvious they can be on film. Always pay attention to background noise. Film in a quiet space if you need to capture a conversation or monologue. Remember, smartphone imagery can easily be manipulated, but poor sound can seriously affect the perceived quality of your video.