Six things from the WebAIM Million

1. There’s a lang attribute on the html element.
2. Link text describes the destination of the link.
3. Every form control has an associated label.
4. button text describes the action that will happen.
5. alt text for images conveys the content and function of each image.
6. Colour contrast is at least: 4.5:1 for normal text; 3:1 for large text (about 24px or 18px if bold); 3:1 for graphics and UI components.