How to start designing a web application with Ruby on Rails?

Question

Ruby on Rails

Good day, friends. I started to learn Ruby on Rails and I want to write a full-fledged application, so to speak, "for myself". And, due to the lack of my Ruby on Rails sensei, the question arose:
Where to start designing an application? Which models should be created first? How to properly build the application structure in your head? Is it possible to create a normal, working application with targeted googling? Actually, from today I started using toster.ru for this kind of consultation. I will be glad to any advice.

Answer 1

It's a bad idea to start an application with descriptions of models. Personally, I develop using the principles of BDD ( habrahabr.ru/post/62958 ).

Answer 2

They always start with direct functionality, that is, if this is an online store, then the basket comes first. Blog - posting. If I use some libraries, I first connect them and test them. For the last project, I needed a form sanitizer, I started with it and checked what kind of result it gives. Sometimes you have to build the code in a special way so as not to rewrite the already finished implementation.
And yes RoR - UG.