At the yearly Joomla! conference called JoomlaDagen Sigrid was giving a presention on "GDPR - a practical guide to comply". You can download the slides here.
In the presentation Sigrid was giving an overview and she was showing a structured way on how to comply with GDPR as a business in general and also with a Joomla based web agency. There were many tipps and examples on how to solve documentation and compliance with technical and organisational measures.