Level AA guidelines
Level AA represents a midrange level of conformance, and includes the biggest and most common barriers for disabled users. In order to meet AA, you need to make sure you are also meeting Level A.
But just don't stop here, there is more you can do! Check out the level AAA guidelines. If you really focus on good design and accessibility, you might be surprised to find out that you might already be meeting them.
To be clear, accessibility is not a checklist or a tool, and doing everything exacly as documented here will not always guarantee an accessible, or compliant site. It's important to note that how you deliver accessibility is unique and completely dependant on your particular site content, and users.
Ensure everyone can perceive content
Based on the Perceivable principle:
Information and user interface components must be presentable to users in ways they can perceive.
Color
Semantics
Static content
Images
Audio and video
Responsive web design and accessibility
Ensure everyone can interact with content
Based on the Operable principle:
User interface components and navigation must be operable.
Ways of navigating
Ways of interacting: Keyboard and focus
Ways of interacting: Touch and mouse
Ensure everyone can understand content
Based on the Understandable principle:
Information and the operation of the user interface must be understandable.
Content
Consistency
Forms
Ensure content is robust
Based on the Robust principle:
Content must be robust enough that it can be interpreted by a wide variety of user agents, including assistive technologies.