How to SEO Categories and Improve Google Rankings

Categories can be great for usability, however many a blogger has lost valuable search rankings, thus blog traffic, to poorly optimized categories. So what to do with those pesky categories?
Some bloggers (myself included) have often used a drop down menu for categories to prevent
<!-- more -->duplicate content issues. However, there is a much better way which can help elevate your blogs search rankings.
Domain Authority vs. PageRank

• Domain authority: A collection of metrics which measures the overall importance of the entire domain. Some of these metrics include site age, number of other domains linking to the domain, and number of trusted domains linking to the domain. However, the benefits of domain authority dissipate three levels down (more on this later).
• PageRank: Its just what it sounds like, the actual rank or authority of the actual page. On most sites the home page has the most inbound links and the most PageRank. The more pages with high PageRank link to a page, internally or externally, determine each pages PageRank.

Google assumes that the most important pages of a website will always be within three clicks of the home page. With each click, domain authority dissipates slightly, and on the fourth click it completely disappears.
If the home page of the blog links to recent posts, those ten recent posts benefit from domain authority. The home page will also link to a page containing the previous ten posts. Those ten posts will also benefit from the domain authority. The third page back of posts will also benefit, however the posts on that page will receive no benefit. So, in a typical blog, only 20 actual posts benefit from domain authority!
Keep in mind though, those pages are benefiting from some PageRank still passed around your site. Here are a few tricks to leverage your domain authority and improve PageRank flow
Getting maximum authority to as many pages as possible

• Display your categories on the sidebar of the blog with plain text links. Dont use javascript or drop down boxes.
• Create as many categories as possible without alienating your visitors. As a matter of fact, your visitors will probably find it helpful.
• Never nofollow category links
• Try to list each post in only one category
• Use noindex, follow on all category pages

Just because a page is not indexed does not stop Google from passing domain authority and PageRank through it to links on the page. So, in effect the category page simply becomes a bridge between two points that allows for the passage of powerful authority to the important pages without risk of duplicate content issues.
By creating 20 categories with ten posts in each category, the effect of the domain authority effect is increased from 20 pages to 200 pages.