Search Engine Optimization (SEO) tips and tricks.
Screaming Frog, Accuranker, Google Tag Manager and Google Analytics.
Check which CMS a web site is using: https://w3techs.com/sites/info/
Analyze your web site for free (Danish): https://analyzeme.dk/gratis-webanalyse-seo-optimering
https://analyzeme.dk/seo-vaerktoej (new link?)
A nice list of Drupal 7 modules: https://www.appnovation.com/blog/7-drupal-seo-tips-rank-better-google
A nice blog post in Danish by Mikkel Demib.
Notes in Danish at Nowa.dk.
Drupal modules
https://www.drupal.org/project/yoast_seo
https://www.drupal.org/project/metatag