1 - Find the blogs that are DoFollow
Part of the trick is to find blogs that have DoFollow comments; otherwise, your SEO comment efforts are not going to mean anything. All you need to do to find them is to be patient and be willing to do a little bit of research.
Every week you must add a certain amount of comments to comment sections online. Make a note of the ones you add comments to, then every week run a scan to see who is linking to the pages in your website. The blogs that have DoFollow will slowly but surely appear on your link reports. Take those blogs off of your lists of blogs you tried, and put them on a list titled “DoFollow Blogs.” You may use your DoFollow-Blogs list every time you want to post a comment with a working link.
2 - Add at least two keywords into your comment
Optimizing your comment is not essential, but if you get the chance then where is the harm in doing so? It is not essential because it may be hard to add certain keywords to your comment, because your comment is likely to be slightly different to the blog post--especially if you are making a counter argument. Still if you can add in any keywords that appear on the blog post or on your landing page then you should do so.
Some clever comment posters may repeat the part of the blog post that they wish to comment upon, and then make their comment. The comment poster will pick a bit that has keywords in, so that his/her comment subsequently has keywords within.
3 - Add at least two keywords into the anchor text of your link
So when you are picking the link to go in your comment section, you should try to pick a URL that has at least two keywords within. Avoid linking to your home page or your sitemap (although you should sometimes). Do not link to pages that are not descriptive, or pages that have URLs that are difficult for search engine bots to read.
4 - Make your comment at least 80 to 150 words
A common mistake is thinking that only adding a little bit of text will have your comment ignored by search engines. This is only true if there is only a tiny bit of text on the whole page (and sometimes even that is read). It is not true if you are adding a comment into a comment section. Nevertheless it is a good idea to add at least 80 words for two reasons.
You want your comment to be a good, well-rounded and thoughtful, it is hard to do in fewer than 80 words. You also want to give the search engine a few keywords and a bit of text within the proximity of your link. A link standing alone or with a small bit of text such as “Great article” may be misinterpreted by search engines as link spam.
5 - Comment more than one time
This is not a cast iron rule, but many commenters will add more than one comment as they reply to the thoughts of others. If all of your links come from comment sections with just one comment then the search engines may start to suspect that your are running a link building campaign. It is unlikely to cause you many problems, but may make Google begin to scrutinize your other SEO methods to check for what may look like Black-hat SEO.
6 - Use keywords that appear in the blog post
This is a clever trick for two reasons. The blog post will be optimized for certain keywords and when people search for those words then the page is likely to come up on the search engine results page. The result has a title and a link, along with a little snippet example of what is on the page. If you have the same keywords in your comment then there is a small (but real) chance that your comment will be the snippet example that appears under the title on the search engine results pages.
Secondly you are putting keywords within the vicinity of your link, which will help the search engines guess what is on the other end of the link--subsequently making the link stronger.
7 - Make your URL link simple, easy to index, and easy for humans to read
Do not put hard to read or convoluted URLs onto comment sections (you should not have them anyway). You receive more direct-traffic if your URL is easy to read and is descriptive. Any convoluted URLs may also have a hard time being indexed by the search engines.
8 - Use good grammar and spelling but not too well
Do not forget that the search engines are not as big of sticklers for grammar and spelling as many online gurus make out. This fact is especially true of comment sections where search engines programmers are aware that genuine commenters do not care about grammar, sentence syntax, and things such as slang expressions.
On the other hand you must try not to spell too many words incorrectly. Try to keep most of your sentences to more than four words. Do not add emoticon punctuation in the middle of sentences, do not use foul language and do not break up your sentences too much or else they become hard to read.
9 - Write a mini explanation line before your link
This will tell the blog readers where the link leads if your other text does not. It will also become yet another indication of what the link actually lands upon, which the search engine may use to clarify its indexing of your landing page.
10 - Don’ts
Some things may damage the SEO value of your comments, so here are a few don’ts. Don’t Spam a link or Spam the same comments on all blog comment sections. Don’t use emoticons/smiley in the middle of the sentences--use them at the end if you must. Don’t use the same anchor text every time. Don’t ignore the comments and links of others. Don’t install more than one link and don’t use foul language, even if the other commenters do.
If you are looking for another secret tip then run a program to count the most commonly used keywords on the blog and the comments section. You must then add that keyword into your comment. The search engine bots will consider your comment more relevant and may reward you with a stronger link in their index.