Understanding Disabilities when Designing a Website: This is “just” another article on how to design a site so disabled people can use it effectively, but I link to it because it produced two good tips I hadn’t read elsewhere:
Place form instructions before the form field
As screen reading software reads content in a linear format, it is important to provide useful information about the requirements of a form field before the field itself.
Provide a focus state for links
As users with a physical disability will often rely on the keyboard for all interaction, it is important to provide a :focus state for links.
I will admit to never giving link focus state a second thought.
If you’re interested in this, I would advise reading Mark Pilgrim’s fantastic “Dive Into Accessibility” series.