Learn how to shoot?
If you are using an iPhone (guessing a late model cause that's what iPhone users usually do, they keep up to date with the latest models) then 9 out of 10, the issue is because you don't know how to shoot.
Case in point...
Is your subject always in the exact center of the frame, posing for you as you try to make sure their entire body is in the picture? When taking scenery are you trying standing exactly perpendicular to the object you are shooting and including everything else around it in equal proportion to the thing that you are trying to focus on?