Sometimes the comment section of a blog can be way more interesting than the entire article itself. In fact it seems as if sometimes the best information is found with in a post’s blog comments. Which is why I hate seeing blogs that haven’t optimized their blog comment sections for SEO.
I mean lets think about it: This is free content on your site that came from users that are engaging your ideas. By that standard this is the type content that you should optimize above all others!
Handle Pagination Correctly
Many blog platforms will give you the option of displaying all of the comments on one page, or breaking them up 5 or 10 per page. I prefer to show them all on one page and let the user scroll down. By doing this you are allowing for the content on the post page to grow and update with every new comment. Which allows for high craw frequencies of the post. However some sites, rely on CPM ad models which means that the more page views they get, the more their ad partners pay. As a result forcing the user to click through pages of comments make better business sense. If you choose to go this route you should handle pagination correctly by using the rel=next, rel=prev tags in the header. This way all of the pages of comments will be consolidated into one entity as far as the search engines are concerned. Thus cutting down duplication.
Store The Data Locally
There are a lot of really great 3rd party plugins and apps designed to make blog comments easier to use, and style. Some of these can cut down on spam management and social integration. However theres a tiny dark secret that they don’t tell you….often times the comments aren’t stored locally. Which means that if the service you are using ever goes out of business, your comments will likely disappear as well. Or if you want to move your site to a platform that the app doesn’t support, you loose your comments then too. In the end, keeping your comments local, on your server means that you will continue to own and control your data/content for as long as you like.
Use Post Canonical Tags
Many platforms create weird URL parameters because of comments. These are the result of navigation links, permalinks, and sometimes “sort” options. The best way around this is to make sure that every post has a proper canonical tag in the head of the HTML. By doing this you are making sure that any inbound link to a comment’s permalink (happens quite often), will provide value to the blog post as a whole. The canonical tags will also avoid duplicated URLs being indexed.
Hopefully the comments on your blog are from real people. If they are real people, they likely have real faces! Therefore you should make sure that any avatars that you have for each comment is optimized just like you would optimize any other image. This might seem silly, but lets say that you have someone famous comment on your post! If their avatar is optimized correctly, then you are likely going to start ranking for that person + the topic of the post, with in image search. In fact some of the results for my name in image search, are from blog comments that I made years ago.
Use the Correct Schema
Not many folks know this, but there is actually a defined Schema for blog comments. I will admit that despite the fact that this one exist, I have never heard of Google using it in any way. But, implementing it is very low effort and seems like it would be a smart move if one day Google actually decides to implement it, you will be ahead of your competition.