The DataTables Javascript library creates a powerful display of your application's data. Some of the features include pagination, server side processing, sorting and search.

Using Bootstrap in your application has become much more simple. Also learn to create some helper methods to make working with Bootstrap much easier.

The routes file can grow to be unmaintainable and messy. Learn to keep things organized by extracting out blocks of routes into their own files.

Mountable Engines are a great way to extract code into its own namespace and allow the code to be reused in other applications. Other popular gems that are mountable engines are Devise and Doorkeeper.

When displaying a count of records, this will generate extra SQL Queries. Learn how to reduce the number of SQL queries called with counter caching the number of associated records.