If you're just starting out creating content with your phone, first impressions are everything. Now of course you can always delete or simply not post the images that don't make the cut, but you still want a lot of options to choose from, am I right?
What I am about to say, you can certainly take with a grain of salt. When you're beginning you're a mobile photography journey, it's best to follow the Rule of Thirds to maintain balance and structure in your imagery.
At the same time, rules are eventually meant to be broken, but you still want to start somewhere!
The easiest way to make sure your images are following the rule of thirds is the Grid feature on your phone. Some people despise using the feature, but manufacturers saw beyond the selfie and knew you can use your mobile phone to create stunning images.
For starters, the rule of thirds refers to the balance & flow of the human eye as it is viewing an image. If an image had 3 lines going horizontally & vertically, there should be even balance throughout the image. See below for an example.
To enable the Grid feature on an iPhone, simply go to Settings - Camera - Grid. Swipe to enable.
Now go on be fruitful and shoot!