Honestly, I learned everything from YT tutorials - just the basic stuff to get a grasp of how those infamous widget trees work. Most of my learning came from a guy called Mitch Koko. The official Flutter channel is also excellent.

When it comes to libraries, I would recommend sticking with built-in features for tasks like image loading or parsing. This actually works quite well, and there's no need to delve into external solutions, especially for prototyping. Dart's factory methods come in handy for parsing JSON from an API, and the internal HTTP package is also very well done (for more advanced stuff there is a package called dio).

The main challenge lies in state management. Be sure to choose the right external stuff. The 'bloc' package seems to be the state of the art at the moment, but if you prefer something simpler, Provider is the way to go. The need for other libraries may become apparent after spending some time on the project.

Flutter is a great choice for quick prototyping. You can build something in a matter of minutes. Many people prefer this way over launching Figma, which says a lot :)