The title of this tutorial is slightly misleading. The only way to master smartphone filmmaking—or anything else—is through practice. But putting aside that quibble, this tutorial by Anthony Gallo outlines most of what you’d need to practice if you want your videos to look professional. Gallo has a clear, easy style, and he provides illustrations that are truly clarifying. One more quibble: the tutorial’s run time is actually 25 minutes, but you can think of that as a bonus.
https://youtu.be/Jg9B9DIFiOA?si=49_vZGsIv4hEs6as