Importance of Page Optimization part two

In general, the following are basic rules that apply to optimizing on-page text for search rankings:

Make the primary term/phrase prominent in the document - Measurements like keyword density are useless (see kw density myth thread), but general frequency can help rankings.

Make the text on-topic and high quality - Search engines use sophisticated lexical analysis to help find quality pages, as well as teams of researchers identifying common elements in high quality writing. Thus, great writing can provide benefits to rankings, as well as visitors.

Use an optimized document structure - The best practice is generally to follow a journalistic format wherein the document starts with a description of the content, then flows from broad discussion of the subject to narrow. The benefits of this are arguable, but in addition to SEO value, they provide the most readable and engaging informational document. Obviously, in situations where this would be inappropriate, it's not necessary.

Keep text together - Many folks in SEO recommend using CSS rather than table layouts in order to keep the text flow of the document together and prevent the breaking up of text via coding. This can also be achieved with tables - simply make sure that text sections (content, ads, navigation, etc.) flow together inside a single table or row and don't have too many "nested" tables that make for broken sentences and paragraphs.

Keep in mind that the text layout and keyword usage in a document no longer carries high importance in search engine rankings. While the right structure and usage can provide a slight boost, obsessing over keyword placement or layout will provide little overall benefit.

Information Architecture

The document and link structure of a website can provide benefits to search rankings when performed properly. The keys to effective architecture are to follow the rules that govern human usability of a site:

Make Use of a Sitemap - It's wise to have the sitemap page linked to from every other page in the site, or at the least from important high-level category pages and the home page. The sitemap should, ideally, offer links to all of the site's internal pages. However, if more than 100-150 pages exist on the site, a wiser system is to create a sitemap that will link to all of the category level pages, so that no page in a site is more than 2 clicks from the home page. For exceptionally large sites, this rule can be expanded to 3 clicks from the home page.

Use a Category Structure that Flows from Broad > Narrow - Start with the broadest topics as hierarchical category pages, then expand to deep pages with specific topics. Using the most on-topic structure tells search engines that your site is highly relevant and covers a topic in-depth.

For more information on segmenting document structure and link hierarchies, see Dr. Garcia's excellent guide to on-topic analysis.

Canonical Issues & Duplicate Content

One of the most common and problematic issues for website builders, particularly those with larger, dynamic sites powered by databases, is the issue of duplicate content. Search engines are primarily interested in unique documents and text, and when they find multiple instances of the same content, they are likely to select a single one as "canonical" and display that page in their results.

If your site has multiple pages with the same content, either through a content management system that creates duplicates through separate navigation, or because copies exist from multiple versions, you may be hurting those pages' chances of ranking in the SERPs. In addition, the value that comes from anchor text and link weight, through both internal and external links to the page, will be diluted by multiple versions.

The solution is to take any current duplicate pages and use a 301 re-direct (described in detail here) to point all versions to a single, "canonical" edition of the content.

One very common place to look for this error is on a site's homepage - oftentimes, a website will have the same content on http://www.url.com, http://url.com, and http://www.url.com/index.html. That separation alone can cause lost link value and severely damage rankings for the site's homepage. If you find many links outside the site pointing to both the non-www and the www version, it may be wise to use a 301 re-write rule to affect all pages at one so they point to the other.

Source: http://www.seomoz.org/article/bg4