What are the 80% quickwins?

• alt texts or attributes for images are missing
• Contrats
• everything usable with a mouse should be touchable on smartphones or actionable through the keyboard
• provide metadata in HTML markup for documents or informations

The 20% left is ARIA.

Another idea for the ‘problematic 20%’ would be to get (paid) help from those affected and/or specialised teams. But both groups would be happy if the organisation booking them already knew the basics, went 80% of the way to accessibility and thus came into the project as specialists for the remaining, more difficult accessibility or UX headaches (a.k.a the 20%).