Composition can be learned, or some just have an eye for good composition. The way to learn good composition is spend sometime at an art museum. Better yet take an art class. Then after you learn everything you can learn about good composition; forget about it and do what feels good to you.
This image was taken in Ethiopia and eve though the tree is my main subject and just happen to fall into the rule of thirds , I did not down it intentionally, it just felt good.