I've been using composer with Drupal for a few years now and I've picked up a few things along the way that have really helped me out. Following on from my post about the anatomy of the recommended Drupal 9 composer file I thought it would be good to expand on that to present some tips.
Here are 7 tips that will help you out when using composer with Drupal.
Automatic Patches With Composer
One of the most useful things I have found is using composer to manage patches to projects. This is possible using a project called composer-patches. You can require this into your project like this.