If you want your photos and videos that you take on your phone to look better, try this time-tested technique used by artists, photographers, and videographers: "The Rule of Thirds".
Imagine your frame divided into a 3 by 3 grid. Now, as you get set up for the shot, align your scene so that important subjects are on one of the imagined lines that dives up the frame.
For example, when taking a picture of a person who is perhaps looking slightly to your left, don't put them dead centre of the frame. Instead, line them up on the vertical "line" on the right side so that the direction in which they are looking has a bit more space in the shot than behind them. Line their eyes on the topmost horizontal line. You will be amazed how this simple adjustment improves the look of your shot.
As another example, if shooting a landscape, align the horizon to the bottom horizontal dividing line, and perhaps a tree or building along one of the vertical dividing lines.