It's important to follow a few basic guidelines to assure your document is readable and accessible by all users.
Accessible documents benefit everyone - not just those with disabilities! For example, accessible documents benefit cell phone and tablet users, as well as students with low bandwidth access. Accessible documents also make it easier for browsers to display them and are much easier to convert to various platforms or formats.
The text "Basic Guidelines for Creating Accessible Documents" at the top of this page is the main heading so it's marked as Heading 1, the subheadings for each guideline have Heading 2 applied, and the "Example" subheadings use Heading 3. This text does not have any manual styling applied (i.e. bold, larger text size, etc.) - the heading feature or style itself applies the visual styling in most authoring applications.
Users who are unable to see images depend on content authors to include alternative text (alt text) with their images that communicates the content of the image they don't see. The alt text should be succinct and include just enough text to communicate the idea without providing unnecessary details. When screen readers encounter an image with alt text, they typically announce there is an image and then voice the alt text audibly.
Authoring tools provide a way for you to add alternative text to images - typically in a dialog box that appears when an image is added, or later in the image properties dialog box.
If an image contains no real information needed to understand the document content, it is considered decorative. Decorative images do not require a description. However, they may still need to be identified as decorative so the screen reader knows to skip them. Important text in the image should be included in the alt text. Images such as charts and graphs that require a more lengthy description may require additional steps beyond adding alt text.
Alt text = "Stack of blueberry pancakes with powdered sugar" rather than "pancakes" or "a picture of pancakes"
Most screen reader software is multilingual and can read content in a variety of other languages. To ensure that screen readers will read a document using the appropriate language profile, the document language must be identified.
It's also good practice to identify the language(s) of any part of the content written in a language other than the document’s default language. With this information, supporting screen readers will switch between languages while voicing the text. Most document authoring tools provide a way to identify the default document language as well as the language of specific parts.
Setting the Language in Word documents - Review > Language > Set Proofing Language
Microsoft Word: Design tab > check Header Row and First Column in the Table Style Options > apply visual formatting as needed