How to improve you development skills

Sometimes you feel that your code is not good enough, that something is not right and you can do better. What can you do? How can you improve that?

So assuming you have created an app and you want to improve the code, you should start asking some simple questions:

Multiple GUIs

Imagine that you would need to have a web,a desktop and a mobile UI for your app. How should you split your code to support multiple GUIs?

API

The big guys provide APIs (e.g you can use Twitter, Facebook, Google+ APIs, etc to integrate those services in your app). What you have to do if somebody needs to integrate functionality from your app in his app?

Asking the right question is very important. Is a clear sign of skill level. Try to think outside the box to understand what should be in the box.