use consistent html from page to page. that way, even if your page is hard to use, a user knowing he has to jump ahead 20 links each page visit saves him ton of time. if each page is different, that predictability is lost. It's like the difference between cooking in your own kitchen versus a strangers. don't make them constantly "look" around.
sectionize everything. the idea is to group related info and features together so that a user can jump to a section, and then find the part they needed. imagine a grocery store without aisles or signs, how would anyone find anything?
like a store, use big signs to point to your most important sections.
h1s for nav, content and footer.
h2 for content sections
h3 for each paragraph (or two or three) of page content.
standard sections include headers, navigation, content, contact info, table of contents, and footers.
add a "skip to" menu, or use ARIA landmark roles.
don't use <br>, use <p> or <ul> tags.
don't put meaning less text ("click here", "more...") inside of links, use the text as a label for the content. ("download page", "NYT article about polar bears").
also, don't repeat yourself in link text, each should be unique; if not possible, use the title attrib to add meta info.
make the text of the navigation menu as short and direct as possible.
Place the most important word first, or asap, in all <H1-5>, labels, legends, and <A>s.
to wit: never label like:
Enter your name, Enter your address, Enter your zip...
realize that there is no skimming, or glancing: they have to wait for steven hawking to read the label to them before they decide if that's what they want.
the less they have to listen to, the faster and easier your site will be to use, which reflects well on you.
if you make a flowchart of how a screen reader user would navigate your site, keep in mind that H tags, legends, and links are the decision points.
blindness aside, more users have movement problems: how well can YOU use your site work without touching the mouse?
that test is easy, relevant, and free.