If you are a WordPress user then you should have the following plugins installed on your WordPress. These are not compulsory for blogging but yes, they are close to compulsory for professional blogging. I would say them 5 must have plugins for successful professional blogging on wordpress,
This plug-in will let you enter the keywords, title, and description for each post. That will help the post in indexing on the search engine.
If you are planning to monetize the blog, then you should have AdSense Manager with you. This will convert the HTML code into PHP and will let you place the Ads properly onto the blog. Very effective and useful plug-in for WP users.
Comments are very important for professional blogging. The comments should be handled properly and the users should get the options to communicate thru comments to each other. That will create a string for your post which will be helpful in long run. The first user who posts a comment on your post should get a “Thanks” or “Welcome” message from you, which will show your etiquettes towards him. WP-Comment Remix will help you in this regard.
The page load time of your blog should be less than 4 seconds. This is very important as the user should not get irritated with the page load time of your blog. You can go thru one of my article on Importance of Page Load timing for having a feel of it. You should have WP-Cache with you, which will reduce the page load time for your blog.
When you start posting 6-10 articles per day, in that case managing those articles will become a difficult task. This plug-in will let you manage the posts from Manage/Post page itself. The effort will become very less as you don’t need to go to each post for changing the variables individually.