Images
All images should have alt tags, or descriptions of the image, added. This includes logos and other header or footer images. This also includes social media posts.
Critical information should not be posted in an image, particularly in emails. Not only are they not accessible to screen readers, but users with slow internet may be unable to load images to read the text.
It is good practice to include a description of yourself at the beginning of a video. The W3C Web Accessibility Initiative provides more information about providing audio descriptions on their website.
It is very important to use alt tags for images that have embedded links. WebAIM notes, "If a linked image does not have alternative text, a screen reader may read the image file name or the URL being linked to."
Source: WebAIM Links and Hypertext