Is it OK to post comments on competitors site with my site url?

Yeah it is helpful to comment on blogs related to your blogs niche. P.S. they will not shun you comment away

i would like to add one more suggestion. While finding a blog or other website for getting link, try to choose dofollow comment link. This will help you to increase your visibility online. It depending on your comment approval.

OP - I would say that you should try to find a good amount of blogs that share the same niche as your own site. This is a good way for Google to see that your site has links from sites of the same topic -so, the answer to your question would be yes. In my opinion, relevant backlinks are useful. Or at least, they seem to be in my own experience.

However, I would also strain to you that if you can land a backlink using your own keyword as anchor text, it might as well be on just about any site. From my own work, I would tell you that a relevant anchor text is just as powerful, if not more powerful, than a link on a page with relevant content.

For instance, I put a backlink on a PR3 .gov site. It had nothing to do with my niche, but I used my keyword as anchor text and I definitely felt the effects of that link!

Try to vary your link strategy - use do-follows and no-follows. Use relevant and non-relevant. Use different anchor text, use the URL as anchor text. Use 'click here' as anchor text. Do whatever you can to make it look as if you didn't set up the links yourself - it's all about appearing as if the links were built naturally over time by other users that found your site useful.

-Noah

-Noah