How to Use WordPress Comment Plugins to Improve a Blog

1. With any WordPress plugin you first download the plugin from WordPress or from the plugin developer. You then upload the new plugin folder by FTP to the plugins directory of your blog (see links in Resources below).
2. To activate the newly uploaded plugin, go to the WordPress admin panel for your blog and choose Plugins from the Dashboard menus. Find the new plugin in the list of available plugins for your blog and click the activate link.

3. For blocking spam, most WordPress users already have Akismet installed and running, so I won't go into obtaining that one. Another good spam fighting plugin is Did You Pass Math? This plugin asks the commenter to do a simple math problem like 'What is the sum of 3 and 5?' to prove that they are a human and not a robot. This plugin is free, but you can donate a small amount to the developer if you find it really beneficial to your blog.
4. For encouraging and rewarding your commenters, Comment Luv is a helpful plugin. This plugin will take a URL entered by the commenter, go to their blog and come back with a titled link to their last blog post to add to the comment. This plugin works on WordPress and Drupal. In addition, when you use Comment Luv on your blog, you can register your site with Comment Luv and keep track of the places where you leave comments yourself. Comment Luv is free.
5. For improving the appearances of your comments, a plugin that will highlight any comments that you as the author add to a thread is Author Highlight. You have to be able to edit the comments.php file and some of the settings in the plugin file to use this one, so it takes a bit of knowledge beyond uploading and activating it. Once you've done these two edits, any comments by you as author are assigned to a CSS class named .highlighted to make your comments stand out from the others in a thread. Author Highlight is free.
6. If you want to allow readers to edit their own comments after they push the Submit button the first time, a plugin that will allow that is Edit Comments XT. The default amount of time the commenter has to edit their own comments is 30 minutes, but you can edit this on the plugin's options page in the WordPress admin area.
7. To show off your commenters and give them some space in your sidebar, the WP-Most Commented Posts is a useful plugin. To use this one you need to add a short line of PHP to the sidebar.php file in your blog and install and activate it in the usual WordPress manner.