The UK ICO published a Code of Practice for use of Data in Political Campaigning for public consultation which ends October 9, 2019.
Though it officially applies to UK-based political campaigns, the code contains deep analysis of GDPR issues and can serve as useful, actionable guidance on compliance to companies and organizations subject to GDPR on topics such as: How to provide privacy notice information and how to determine whether your profiling might have a legal or similarly significant effect.