Operable

People with disabilities must be able to Operate your web content. The Operable principle is all about removing barriers between your user and your content.

https://developer.mozilla.org/en-US/docs/Web/Accessibility/Understanding_WCAG/Operable

Obvious focus indicators

Allow enough time

Disable distracting content

Descriptive page <title>

Provide alternatives to complex interactions

Keyboard navigation

Keyboard Compatibility
https://www.w3.org/WAI/perspective-videos/keyboard/
Keyboard Accessibility
https://www.nngroup.com/articles/keyboard-accessibility/
What are Keyboard Traps?
https://support.siteimprove.com/hc/en-gb/articles/114094037151-What-are-Keyboard-Traps-  

Help users navigate

Touch Gesture Guide
https://static.lukew.com/TouchGestureGuide.pdf  

Careful with flashing animations

According to the Seizures and Physical Reactions guideline, animations should never flash more than three times per second.

Photosensitivity and Seizures
https://www.epilepsy.com/learn/triggers-seizures/photosensitivity-and-seizures  

Make link purpose clear

According to the Navigable guideline, link text should be descriptive.
 

Semantic heading structure

For example, when providing headings (<h1>, <h2>, <h3> etc) headings should reflect hierarchy of information, as well as each heading should descriptive of the content that follows the heading.

Headings | Usability & Web Accessibility
https://usability.yale.edu/web-accessibility/articles/headings
 

Generous target sizes

According to the Input Modalities guideline, interface target sizes should be a minimum of 44 x 44 pixels.