In this articles we are going to look a bit closer on techniques you should avoid when trying to build links to your site. The technique listed in this article will hurt your website or be a waste of time because they provide no value what so ever.
I am not going to include buy links on this list. This is due to the fact that the technique can be very effective although frowned upon by Google. I do not recommend buying (and selling) links. You can read more about why this is in another of my articles that you can find here.
Blog commenting is a very popular method to build links. It is a method that I never recommend. It is not very effective and can do more harm then good. Lets start by addressing the fact that most comments that are left for link building purposes does not add to the conversation and does nothing more then clutter the Internet. Some blog commenting is pure spam while others try to make an effort to make it seem more natural but in most cases it will still be worthless posts. If you want to actually leave good comment it is going to be very time consuming and the results you see will not be worth the time spent. A good link is worth 20 blog posts or more. You can out compete any competitor even though you have a lot fewer links if they build blog comments and you build quality links.
Forum signatures can work if they are done correctly. If you leave high quality posts on relevant high quality forums. It is however no where near as effective as it used to be a few years ago. Finding forums, signing up and contribute in a way that is going to earn you valuable links will take a lot of time . More time then it is worth. Most links will be weak and the first link from each site is the most valuable. The more links you get from the same site the less value you will see from each link. This is why I do not think it is worth building forum links / Forum signatures. The amount of work required to get that link is too high. It is not worth it unless you have a lot of time on your hand and no better way to spend it.
Guestbook spam is completely useless today. It does not contribute any value at all and less then 1% of all guestbooks are cached by google. This is unlikely to hurt you unless you build a very large amount of links. But it is also unlikely to provide any benefit. It is simple a waste of time and a very scummy thing to do.
Most directories are a waste of time. Webmasters used to rely on them too much which caused a very high number of low quality directories to be built. Google has therefore devalued most directories. There are a few high quality directories such as BOTW that is still worth getting a link in but there are currently no free directories that I consider it to be worth getting a link from.
Private blog networks
There are a lot of different private blog networks that allow you to buy links on a large number of different websites for a low price. The price per link can often be less than 1 USD per link. Never buy links on these networks. It will not provide any lasting positive affect and might cause your site to be penalized. It can be very hard to rebound if your site get penalized for buying links on a PBN.