Seo Wizard checks things you're bound to forget.

It checks, for instance, if you have images in your post and whether they have an alt tag containing the focus keyword for that post.

It also checks whether your posts are long enough, if you’ve written a meta description and if that meta description contains your focus keyword, if you’ve used any subheadings within your post, etc. etc.

The plugin also allows you to write meta titles and descriptions for all your category, tag and custom taxonomy archives, giving you the option to further optimize those pages.

Write better content

Using the snippet preview you can see a rendering of what your post or page will look like in the search results, whether your title is too long or too short and your meta description makes sense in the context of a search result. This way the plugin will help you not only increase rankings but also increase the click through for organic search results.

Meta & Link Elements

With the WordPress SEO plugin you can control which pages Google shows in its search results and which pages it doesn’t show. By default, it will tell search engines to index all of your pages, including category and tag archives, but only show the first pages in the search results. It’s not very useful for a user to end up on the third page of your “personal” category, right?

WordPress itself only shows canonical link elements on single pages, WordPress SEO makes it output canonical link elements everywhere. Google has recently announced they would also use `rel=”next”` and `rel=”prev”` link elements in the `head` section of your paginated archives, this plugin adds those automatically.

Social Integration

SEO and Social Media are heavily intertwined, that’s why this plugin also comes with a Facebook OpenGraph implementation and will soon also support Google+ sharing tags.