Search Engine Optimization, a rather popular, yet misunderstood topic. SEO promises increased page views by appearing as close to the top of a search results page as possible. Naturally, this requires optimizing towards specific keywords related to the content of the site being optimized. There are many common sense things that can be done to increase pagerank, but there is a ton of bad advice going around. After reading several articles on SEO which offered poor advice one can advise against some poor choices.
Multiple (identical) links to the same content are not bad. People tend to confuse, multiple pages containing the same content, and multiple links (on separate pages) to a single page that contains content. Cross linking is beneficial, not only for SEO but also usability. In WordPress (since 2.3), there are three methods of organizing posts, archive by date, category or tag. In most cases using only one of these for organizing data is not wise. Tags and categories and work together, as visible on this blog.
Contrary to popular belief, WordPress only generates one permalink to a particular post. Sure all the different ways to get to a post still work if manually entered. The links WordPress generates, however, result in only one location for a page, independent of taxonomy (it is all in the permalink structure). Need proof? Look at the link to this post. Visit the archives of the tags this post belongs to. Then visit the archives for the category this post is in. Lastly visit the by date archives for the day, month, or year this post was published. Notice how all the links are the same? This is by design, WordPress does this naturally, and it does not adversely affect pagerank.
Do not use nofollows. Simply put, the nofollow attribute produces a contradiction of intent. What is the point of creating an hyperlink if the user (be it human or robot) is not supposed to follow it? Sure, they do have a use for linking to outgoing content in things like user comment. However, in sections where the content is fully controlled (e.g., blog posts) why instruct the user not to follow the provided links. Under no circumstances should an internal link contain the nofollow attribute. If internal content is not trustable, then there are greater problems to worry about than pagerank.
Never substitute usability with SEO. A user may find a your site faster, but if they can not navigate the site they will not stay long. Someone suggested that a usability enhancer (breadcrumbs) should only be used on pages (not categories) as a SEO tip. Sadly, this is completely wrong and is detrimental to usability. Breadcrumbs should be placed in the same location on every page of a site if implemented. The single exception is for the front page, but thats an entirely different story.
[end of transmission, stay tuned]