After the famous Google Penguin Update, the importance of hard-to-get quality links has become clear to all. What you should aim today is to get links meant for humans, not for Google.
So what does this all mean?
Linking from relevant places
Don’t just submit links to different directories just because they are directories. Choose the best and biggest ones, where people actually go to look for websites. Examples could be Dmoz.org, Yahoo! Directory, etc.
If you want to make blog commenting, do it only if you really have something smart to say and you believe that the link you are posting in a comment provides some value to the blogger, or other readers. Otherwise, just skip it.
I could go on and on about this, but what I really want to say is that you should avoid all kinds of link building activity where the main purpose is just to get SEO optimized links and affect to your search engine rankings.
You want to be linked from places where you are having actual audience that might see your link and click on it directly to visit. You want the links from these kind of places that believe the link will benefit some human beings by providing them more information beyond what’s on the page itself, not because they are thinking the link will benefit someone to rank better.
Yes I know, earned links are not easy links. But they are worth it, or at least they won’t lead you to get penalized by Google.
Unnatural looking links
So what are then unnatural looking links? The examples I am going to give you are based on the examples I found from Search Engine Land’s article Can There Really Be 85 Types of Unnatural Links. (Don’t worry, not going to list all 85 types.)
1. You have a link from a sports bar based in Paris to your boxing club in Birmingham. This is a classical unnatural link that has no natural connection in subject matter or location between these two websites.
2. The title tag and the heading tag of some of your internal pages are the exact keyword match for several anchor text links from other websites pointing at your site. This is clearly unnatural.
3. Your less-good-blog or site has ten times more blogroll links than your nearest competitor. The amount of links should go hand in hand with the quality of your website. If your bad quality SMS loan site has 100 blogroll links, it will be seen as unnatural.
4. If your website has 1000 unique domains linking to it and 400 of them are coming from some directory, or file named /resources-links.html, links.asp, or /exchange-links.html, it is definitely unnatural. When half of your inbounds originate from links pages, that is unnatural.
5. Your site has a high amount of incoming links, but all these links are coming just from few resources.
7. Blog networks and article networks.
8. Mass directory submissions outside of your vertical.
9. Link(s) from (a) site(s) that offers no contact information, author name, etc.
10. Blogs with 3 external links from each blog post: one link to Wikipedia, one to .gov or .edu site, and one to a client site.
There are surely more different types of unnatural looking links, here was listed only 10 of them. Please go and read the article published in Search Engine Land (natural link above) if you are interested in reading further about unnatural looking links.
What is a good link profile then?
Good link profile is diverse. There are links from blogs, static pages, news websites, directories (good ones), social media bookmarks, etc.
Some of the links can be SEO optimized links, but majority should be just natural links, placed by webmaster. These include URL-links, brand links, long-tail keywords, just some word like “read more here“, etc.
It is very important to vary the anchor text, also the top level domain (.net, .com, .org, etc.) and geo location of the site linking to your site.
The link types should also vary: some links should be permanent, some footer links, some links from sidebar, some links should point to your subpages, some links should come from other website’s subpages, some from the homepage.
Important is just to try to have the link profile as diverse as possible, and of course, natural.