If your website is based on WordPress then there are several WordPress plugins that can help result in better SEO and usability, and deliver improved conversions. Listed below are some excellent plugins. The best part is that most of them are available for free.
WordPress SEO by Yoast
This extremely popular plugin is also one of the easiest to use. Created by Joost de Valk, this plugin improves almost all SEO aspects of your website including insertion of high quality keywords on your website.
Widget Logic
This plugin is very useful for your widgets as you can now control the placement of your widgets. You can easily control the content of your site using this plugin. However, you need to have experience in using PHP coding since errors could result in severe problems.
Use Google Libraries
This easy-to-use plugin can be used on your server with the help of CDN from Google itself. This plugin can be used in place of JavaScript libraries and can help save valuable bandwidth by storing your scripts in compressed form. Since these files are already cached by most users, the performance of your site will certainly improve when you use this plugin.
Gravity Forms
This paid plugin starts from $39 and can take care of all your generated forms that range from basic contact forms to all of your content management. In addition, you have integration of MailChimp as well as easy creation of content including all pages and posts on your site. Finally, this plugin also allows export of all entries in CSV form and you can also import and export all your forms for backup or for use on other sites.
Twitter Feed Pro
This paid plugin developed by Alex Moss costs $19.99. This plugin can customize the output of your tweets as well as combine them with tweets of others. You can also view public mentions and replies as well as view favorites by username while searching for any hashtag or term.
This plugin has Twitter API v1.1 compatibility and uses HTML for output of tweets instead of jQuery.
Simple URLs
This plugin allows you to track all your outbound links including affiliate links and control them from your WordPress backend. You can also stop authority from going through the link by adding Disallow: /go/ in your robots.txt file. You can easily calculate conversion rates through affiliate links by using this useful plugin.
Lightbox Plus and NextGen Gallery
These 2 plugins work together to manage your image gallery. You can certainly improve your SEO by defining alt tags, image titles, etc. You can add customized templates that can be used with NextGen shortcode.
Members
As the name suggests, this plugin can help you get additional control in WordPress. You can edit and add user roles as well as limit the content for specific users. This plugin offers several shortcodes and widgets that are quite easy to use.
W3 Total Cache
This powerful caching plugin allows you to combine and minify JS and CSS to HTML linebreak as well as removal of comment, disk and browser caching, and a lot more. W3 Total Cache also plays nice with WordPress.
You should try the above free and paid plugins for WordPress to finally use ones that best suit your website and business model. You must ensure that you finally use trusted WordPress plugins for your own website or those of your clients.