Learn the Facade Design Pattern, when to use and how to implement it.
Learn the Command Design Pattern, when to use and how to implement it.
Learn the Decorator Design Pattern, when to use and how to implement it.
Learn the Observer Design Pattern, when to use and how to implement it.
Learn the Builder Design Pattern, when to use and how to implement it.
Learn the Adapter Design Pattern, when to use and how to implement it.
Learn the Factory pattern, when you should use it and how to implement it.
Learn the Factory Method pattern, when you should use it and how to implement it.
Learn the Abstract Factory pattern, when you should use it and how to implement it.
Learn how to handle API breaking changes. What is considered a breaking change and what is not. Includes examples of how to implement versioning in ASP.NET