Folder structure

Every feature should be encapsulated in modules. Every module should contain all necessary functionality it implements, it means:

components
models
services
directives
functions
etc.

If some functionality is already implemented (services, models, etc.) you should refactor it to shared folder, that it will be available to other modules. Main rule is that module should be transferrable to any other app or library without much coding.

Feature modules can be nested into another feature module.