Goolge’s algorithm is constantly changing on an almost daily basis, and backlinks which used to help your website rank higher, can quickly become toxic and do you more harm than good.
At the very least, if you are still actively building these following kind of links, you are probably wasting your time and effort, and you would be better focusing your attention on other strategies.
About ten years ago, running software which crawled the Internet to find blogs to comment on might have given your site a slight boost in the SERPs, but these days, all that you are likely to get is a penalty from Google. Most quality blogs do not allow links in comments any more, and if they still do, they are almost certainly “rel=nofollow”, so they will not pass on any link juice to your site. Still, this does not stop people persisting in trying to build blog comment links with software.
The only kind of blog comment links that you want is one that you have done yourself and that adds genuine value to the original post. If you take the time to comment on a few relevant blogs and add value, you might find that you get some real traffic to your site from it.
Bulk Web Directory Submissions
The days of submitting your website to hundreds of low quality directories and seeing any benefit have long gone. Google have devalued these kind of links to the point where they are pretty much useless. The only kind of directory worth submitting your site to is one which is a niche specific one that manually approves all of the listings.
Also, if you do go down the road of submitting to directories, make sure that you do no use over optimised anchor text, as this can lead you to fall foul of Google. Simply use the URL or brand name as the anchor text and you should avoid any trouble.
Site-wide Footer Links
In years gone by lots of webmasters would buy links in the footers of websites with the anchor text being the keywords that they were trying to rank for. These links did have quite a bit of weight for a while, but Google soon put a stop to that, and now you are risking a penalty if you go about doing this much. If you own a few websites and you want to interlink them in the footer, you shouldn’t have any issues, however doing it on a large scale basis is potential suicide.
Low Quality Guest Posts
Google have warned webmasters on a few different occasions about engaging in low quality guest posting. This does not mean that you can not guest post at all, because there are a lot of occasions when it is a great way to get a link from a trusted site, however, if you post on a lot of sites that accept poor quality content then you are heading for trouble. Google famously penalised MyBlogGuest and all of the site which were using it, so their stance on the issue it pretty clear.
Websites such as Ezine Articles, were very popular a few years back because they allowed you to post an article about anything and add a link back to your website to it. SEOs soon jumped on this opportunity and built links to their sites from every article directory that they could find. A lot of the content on these sites was very low quality and often spun content, so Google devalued the links and now they are worthless. If you are going to write articles for SEO value, try and make sure that you get them posted an high quality sites. This will take a lot more time and involve reaching out to a lot of different webmasters, but the links that you will get will be of a much greater value.