There isn’t much that you need to do to optimize your smartphone for video. The default settings are usually correct. However, if you want to be sure, double-check that you are recording 1080p at 30 frames per second. You can record at 60 frames but that is usually a setting for action shots.
If your phone has 4K capacity, I suggest you DO NOT use it since it’s overkill in most cases.
In this video, I show you how to check your settings on an iOS device and an Android. Not that your phone may be slightly different.
One more tip: Try different settings out. You may like the look of 60 frames per second or using a filter.