Link building is without a doubt the most time consuming—but most rewarding—aspect of search engine optimization. It usually takes more effort to promote your content (build links) than to actually create it. As I have stressed repeatedly before, compelling, useful content should make your link building efforts much easier.
Before I go any further, let me note that I have a slightly different perspective when evaluating link-building tactics than most SEO consultants. I do SEO primarily for my own sites and my income depends on the ability of those sites to make money. That means that I try to build links that primarily offer long-term value. I still try to get the short-term and medium-term value links, but I like to build authority for my sites. If you’re working for a client or a boss that wants to see immediate results, your priorities will probably be different.
In situations where I have to pay or put some serious effort to get a link, the most important criteria is always: Will the link send useful, converting traffic?
Why is this my most important criteria? Let's explore three different scenarios to illustrate this:
Jennifer is a link-building analyst at a small SEO agency. Her job is to select the link sources for her clients. Most clients want to see results instantly. She knows that the easiest way to get links and potentially good results is from directories. It doesn't matter if nobody knows about the directory. If it has a high PageRank and the cost is reasonable, she goes for the link. The result is that the site might experience a boost in rankings—temporarily—and the client will be happy—temporarily. Hopefully, long enough for Jennifer to collect payment for her services!
Obscure directories are visited by search engine crawlers, but they are rarely visited by users. This might result in fleeting search engine rankings, and subsequently visitors from those rankings, but ultimately the search engine's purpose is to follow the user. We (as webmasters) are the ones casting the votes by creating the links. Eventually search engines get 'smarter' and discount these directory links. I assign them a low weight as the probability (risk) of these links losing value is very high. They are of short- to mid-term value. I pursue them for my sites, but they are low on my priority list.
Now, Susan is an in-house SEM analyst. She needs to drive sales to the company's website. She does so primarily via PPC as the results are immediate and effective. But she also complements her strategy with SEO, pursuing organic links that will primarily send converting traffic to the site and maybe even higher search engine rankings.
I assign medium weight to these links. As I said, search engines need to follow the user if they want to be successful. The result is that they will have to follow these links eventually, and that will result in search engine referral traffic.
Let's take for example forum signatures or Wikipedia links (which are 'no-follow'). Even though I know these links are not very useful at the moment for link juice, the referral traffic is excellent, because it's highly targeted, and best of all, some 'influencer' might read your post and potentially provide a direct link from their blog or site, tell others and so on.
Search engines are currently following these patterns via their surveillance tools (browser toolbars, analytics, etc.). Whether they are using the data is a matter of debate, but they will eventually use this information to tell if a link is really valuable or not. That’s ultimately their purpose, isn't it?
Our final link builder is Aaron, a well-known writer with a big following on his blog. Most of his posts are useful and naturally linked to by other bloggers in his industry. Search engine robots follow and trust the links, and so do users. He gets direct referral traffic, as well as good rankings when search engines rank his pages for the relevant terms. This is the ideal case. You get good rankings as well as direct referral traffic from visitors. I assign strong weight to these links.
As I have mentioned before, the way to do this is to build your site into an authority in your specific niche. Easier said than done, I know! It takes time, it is more difficult to do—but is definitely rewarding. Rome wasn’t built in a day, after all.
What is your most important criteria? Speak out in the comments section.