I'd have to put blog commenting very high on my list of underrated SEO tactics. And it's both good and bad. A high-quality, relevant comment on an active blog can be GREAT for exposure - it can launch profitable relationships, drive traffic and sales, and so much more.

But it's also bad because comment spam -- the worst kind, the low-quality irrelevant tripe that so many people post with keywords as their username -- still seems to be effective in some search/keyword spaces.

I'd agree with Matt and extend that to any type of positive online interaction...and by positive I don't just mean agreeing with a post, I mean being respectful even when you 100% disagree with someone, and bringing something to the table rather than just being a jerk or a bobblehead nodding in agreement. Also I think that offline relationships truly help online ones. There's no substitute for human interaction.

I also think nice, easily updateable code is a good tactic, partially because if someone else needs to get into your code and change it, it helps if it's written to a common standard and written to be efficient. I don't think that Google's going to run screaming if you have a few errors but I do believe that major code issues should be addressed and corrected. If your site isn't properly spiderable because of code errors or errors with redirects, you really need to fix that.

I would say the the use of analytics to identify low-hanging keywords worth putting emphasis on is hugely underrated, particularly since this technique can be used to not only optimize relatively high-volume keywords, but also keywords that are known to convert well.

I think one of the most underrated tactics is getting your site setup properly on the server.  So many of the clients we get have 10 ways to access their "homepage" - just getting redirects and 301s in place can have a tremendous positive impact on your rankings - and a lot of large corporate sites haven't been setup correctly.  Focusing inbound links to the right place is huge...

Good stuff already mentioned.  I'll add one that I feel not only is underrated, but often gets overlooked: Unique & Relevant Images.

How many pages do you find in the SERPs without page specific photos or graphics?  How many with?  Not only do they go hand in hand with ranking in universal searches, but they will get linked to more often.  Win Win!

Internal linking....so few do it effectively (if at all)

KenLyons nailed it on the head... Internal linking.  So many times you see sites losing out on better rankings because they can't link properly between pages.  Many times I have seen e-commerce pages that will typically offer 'suggestions' but the product image will only be linked (sometimes without any alt tags) instead of the product name.  This is a great opportunity to add an internal optimized anchor text link!

Though probably not considered underrated to folks commenting here, I agree with Ken that internal linking is sort of a hidden giant in terms of how underutilized it is, particularly on larger enterprise-level sites.

There's a ton of ROI that's left on the table there.

I would add a well-optimized Google Places page especially if the business isn't in a crowded niche.  Not quite SEO but for many businesses, local search is their only opportunity to get natural search exposure and so many Places pages remain unclaimed.

Technical issues and site architecture like what @Traveler and @KenLyons have said above.

If those are done properly, then next most important things are keyword research and Title tags.

Dear Jill,

many thanks for the great info!

was wondering, if us users also have a profile link, and rss-feed?

thanks,

Bob :-)

Sorry, Bob, not sure I understand what you're asking in the context of this discussion.

Great suggestions!  I'm only 2 months into a new blog and site, so i'm very new at this.  I have noticed one thing that seems interesting and I don't understand.  My pages on their own don't show up high on Google for a given search, even though I have lots of keywords, etc.  However, if I create a post on Buzzfeed with the same content, the post will show up high on page 2 for the same Google search.  Any ideas why that happens or other ideas for newbies?  Thanks!!

Oh man! Not just one but several people took mine.

Even though everything in me wants to make a case for analytics, I'm going to go with internal linking - especially within blogs. When I look up a site in OSE and see its top pages and then see how seldomly the site links to those pages, I get kind of excited. It's such an easy win. There's a reason those pages have page authority (provided you're not gaming the system and just haven't gotten caught yet). Find the pages other sites say are valuable and make sure you look for opportunities to link to them.

But also keep me on your site longer. How many times do I read about some reference to a current event on a blog with no link to the event the writer is speaking of? I think the best at it is Jakob Nielsen. Even though his site is the single wide of the web, whenever I go to it I don't leave soon b/c he pulls me in to other articles he's written and studies he's done.

To all above who mentioned this, I will reiterate internal linking as a hugely overlooked strategy.

One protip for blogs is to install a related posts plugin, which will automatically link   related posts together.  This is massively effective on  blogs with a high post count.

Contacting suppliers/partners/associates etc you have an established relationship with and asking for a link, probably more a low hanging fruit tactic than an underrated tactic - deserves a mention nevertheless

Internal linking    every  important。。

Hmmm.....Meta keywords or keyword density. Probably the former......I kid, I kid.

It's not a direct SEO tactic but building relationships with people in your niche can have a lot of mileage.

"It's not a direct SEO tactic but building relationships with people in your niche can have a lot of mileage."

That deserves the 2011 Award for Spotlighting the Most Underrated SEO Technique

Let's not see any more articles advocating the use of blog comments for SEO -- that is now completely a spam tactic simply because so many people recommend it.  It has lost all positive value and is nothing more than a nuissance.

Linking out. SEOptimise ranks on #1 for [seo blog] in the UK mostly based on linking out.

Image optimization. It simply baffles me when major corporations don't habitually augment images on their own websites with basic alt text (yet have complex marketing strategies!)

Wow, who and why voted me down?

IDK, but I voted you up Chef. (*Goes off to buy seoblog.co.uk ;) ).

I'm a big fan of making sure your meta description inspires a click.  Most people still just try to stuff keywords in the meta description, even if they're written as complete sentences, but keep in mind that it'll show up on the SERP right below the title, so the text should flow, and should ideally have a call to action or motivating phrase that gives people a reason to click through.  It's easy, but often overlooked!