Our blocks are generally made up of up to 4 files:
|- block.js
|- editor.scss
|- index.js
|- style.scss
The only required file is index.js, this sets up the block using registerBlockType. Each block has edit and save functions.
The scss files are split so that things in style are added to the editor and frontend, while styles in editor are only added to the editor. Most of our blocks should use core components that won't need CSS though.
A simple edit function can live in index.js, but most blocks are a little more complicated, so the edit function instead returns a Block component, which lives in block.js. By using a component, we can use React lifecycle methods to fetch data or save state.
The Newest Products block is a good example to read over, this is a simple block that fetches the products and renders them using the ProductPreview component.
We include settings in the sidebar, called the Inspector in gutenberg. See an example of this.
Other blocks have the concept of an "edit state", like when you need to pick a product in the Featured Product block, or pick a category in the Products by Category block.