If you are going to use WordPress to manage your web presence (why would you use anything else?), you need Yoast. Yoast is mostly known as an SEO optimizer plugin, but it does much, much more. Many indexing tasks are automated, making your site structure sleek and well organized.
There are two versions of the software, and the basic plugin is free. You get most of the features of the Pro version, and if you are a blogger that isn’t trying to make money, then it is great. If you are competing for search engine ranks in the content monetization wars, you’ll need the extra keyword support and other features that the Pro version supports. There are a ton of analytic tools that can make spotting errors—and then fixing them—quick and painless. Once complex tasks like laboriously building XML sitemaps are built into the Yoast functionality, and you won’t even realize they are there unless you dig amongst the many features included in the software. If you have no idea what SEO is, you should probably install Yoast and leave everything on the default settings while you watch the tutorial videos on the Yoast website. Of, course there are tons of YouTube videos available as well; with over 1,000,000 active installs, Yoast has no shortage of fans.
In addition to being my number one pick for WordPress Plugins, the Yoast site is awesome in its own regard. There are tons of helpful tutorials and help documents that can help you de-stress the learning curve when it comes to SEO and WordPress administration. If you do decide to upgrade to Pro, you may run into problems uploading the upgrade files unless you tweak your settings on the server. WPThemeSpeed has a YouTube video to show you how to fix this for GoDaddy customers.