How to better write a method body that contains business logic

Specific methods: First write the method body of the main process, the details of the first abstract method is not realized, and so on after the completion of the main framework to achieve specific details.

Why: The previous approach was to build a method and then plug the code of the business logic into the method. The problem with this is that if the business is complex it can lead to confusion, and later code is not easy for others to understand.

How to better write a method body that contains business logic