What is the best way to structure an HTML document for SEO and accessibility?

Question

What's the recommended way to structure html that includes navigation so it's still SEO'able and accessible.

For example, should the structure be more like that of a document:

1. Skip to content (link, hidden by CSS)
2. Navigation
3. Content
4. Other content (right hand panes etc)

or:

1. Skip to navigation (link, hidden by CSS)
2. Content
3. Navigation
4. Other content (right hand panes etc)

Obviously CSS is used to control the layout, but bots and screen-readers ignore the CSS.

Answer 1

I've been asked to move the navigation after content by a client before, but I don't think it helped them much. I generally follow the first structure you mention above.

Some random tips:

• Keep your markup standards-compliant, valid and simple.
• Don't stuff keywords or anything.
• Treat headings like they should be treated. Make sure there's only 1 h1 tag. Use headings sparingly across the page (Google - in the PDF download).
• Use title attributes on anchors and alt attributes on images (but only if the image needs a text equivalent for some users).
• Use rel="nofollow" to direct PR juice to pages you really want them to go to.
• Keep content unique for each page.
• Use Google webmaster tools and MSN and Yahoo!'s equivalent.
• Build, submit and maintain sitemap.xml files.

Answer 2

Any page that doesn't have it's content stashed away in Flash or similar is SEO'able. The web crawlers tend to strip everything and read the page as a text stream. Some pay attention to your keywords, their use in the body text, H1 & H2 tags, page title and even domain name but I don't think they are affected by the order of page structure.