A complete Google Tag Manager Form Tracking guide. Learn to track standard, AJAX and custom forms with little or no input from developers.| Analytics Mania
Here is a whole bunch of Google Tag Manager debugging tips that will help you be sure that your setup is properly tested.| Analytics Mania
A comprehensive guide on how to use the Google Tag Manager Preview mode (a.k.a. Google Tag Manager Debug mode) and catch errors faster.| Analytics Mania
A comprehensive guide to building custom templates (both tag templates and variable templates) in Google Tag Manager.| Simo Ahava's blog
| productforums.google.com