In the post-Penguin update by Google one of the changes to how sites are ranked that had the most impact on site rankings is the presence of too many links using the same anchor text pointing to sites. If your backlink profile has too many links with the exact keywords that you want to rank for in the anchor text of those links then Google may penalize your site.
Several industry leaders have studied the effect of the Penguin update across a variety of industries and the results vary but one thing is obvious, to make your backlink profile Penguin safe, your un-targeted to targeted anchor text ratio may need to be adjusted so that it is roughly less targeted and more un-targeted.
SEO blogger Jonathan Leger has recently published some interesting results that show the exact match anchor text average for top ranking website in the post-Penguin search results on Google.com to be around 10%.
Additionally Jonathan's findings indicate that Google may not be punishing exact match domains - domains which rank for the entire phrase that their domain consists of, i.e. pixel crayons (pixelcrayons.com) - many of those types of domains are ranking high with 40% or more of their back linked anchor text being an exact match. Read more from Jonathan Leger's research into this issue here.
How Should You Be Link Building In The Post-Penguin Search Sphere?
What types of links are most effective after Google's Penguin update? The answer is simple. The Penguin update did not target a specific type of backlink, it targeted and devalued the backlinks pointing to sites that had backlinks in place for the sole purpose of influencing their position in the search results. If you own a website you may choose to link to other websites based on editorial value but know that linking to a site that has been penalized may negatively affect the position of your own website in the search results.
Obviously the last thing you should do is generate backlinks to your website through forum profiles and blog comments en masse as that can only worsen your situation and standing in Google. Although some SEO companies are at the time of this writing choosing to replace links for clients that have been devalued by the Penguin update with more of the same type of spammy links -and- are seeing improved rankings for their clients as a result, it's only a matter of time before Google rolls out Penguin version 2.0 and devalues those replaced links too. It is worth noting that generating a handful of backlinks on forum profiles, signatures and blog comments is perfectly fine if the content that you produced in those forums and blogs adds real value to the conversation. It becomes a problem when those backlinks pointing to a single website begin to number in the thousands and the content that you generate does not add any value.
So the question that you should be asking yourself is not "what type of links should I be trying to acquire?", but more along the lines of "how can I really up my game in the type of content that I create for my website and improve the way in which I disseminate that content out in front of people that I know will love it enough to link to it?"
I'll say it again in case you weren't paying attention: Stop looking for backlinks and spend more time on developing drop dead, kick ass content for your website! Content that is high quality, no filler or fluff. Develop a content publishing calendar and stick to a regular frequency of publishing content for your website. Get it out there on Facebook, Twitter and/or LinkedIn, whichever venue is most appropriate to your audience. If your content is up to par and people appreciate it, they will naturally share it and/or link to it. It cannot be stressed enough though that you will constantly need to be finding fresh ways to engage your audience from within your content. You need to keep them engaged and that will not be easy all of the time.
Does that mean you don't need to build links to your website anymore? No, it means you should still take a link when opportunity presents itself. Just don't put as much focus on link building in the way that many link builders did pre-Penguin and still do today. Links still have value for reasons aside from SEO. They can provide a steady source of referral driven traffic and yes the right links can still have an impact on your search engine rankings, albeit in a much more narrow and focused way.
In the search engine optimization industry, SEO companies who have put more emphasis on helping their clients create real value for end users through higher quality content are much less likely to be affected by Penguin. If your SEO company is not up front with you about this then you should be jumping ship now! Before they cause real damage to your position in Google.