As I've mentioned previously, link-building is one of the most important aspects of SEO (Search Engine Optimization). It seems that there are SEOs these days who would like to see blog and forum commenting done away with completely, but I disagree with that (as I imagine most people actually doing SEO full-time today do as well). It can be a challenge to find good, relevant, non-spammy blogs to either guest post on or leave genuine feedback on, so I hope this method helps out a few of you who are faced with the timeless and inevitable challenge of building links. In order of steps:
1 - Visit Google Blogs.
2 - Type in one of the keyword terms that the content on your landing page focuses on. Don't be afraid to use quotes around your keyword term if it contains more than one word. Ex. "Nickel Cadmium"
3 - On the left-hand column, you can sort your results by time/date. I usually like to start with "last hour," then work my way down to "past week." This will allow you to find fresh, hyper-targeted blog posts to browse through and cherry-pick the best-of-the-best!
When you do this, make sure that you're not just picking spam-filled blogs that scrape content from somewhere on the Web. It's pretty easy to figure out which blogs are spam/auto blogs due to how they look, how their content reads and how their content is formatted. Because the content you will be finding is so new, it won't behoove you to check out any of the metrics that exist for gauging the strength of a page, so if you're concerned about that, just go take a look at the home page of the site and gather all the metrics you typically do (PageRank, mozRank, mozTrust, Alexa Rank, Compete score, et al).
Additionally, if you want to see how that site's content typically performs, try using SEOmoz's Open Site Explorer to find the strongest pages and number of unique root domains linking to them. If you don't know how to do that, then go to Open Site Explorer (sign up for a free account so that you can view stats for 20 pages), search for the domain you're interested in (don't forget to consider both www and non-www versions of the site if they don't 301), then click the "Top Pages" tab in the results. Voila!
As for "nofollow" and "dofollow," it's your judgment call. Do you want to have a more natural-looking link profile? If so, then just go ahead and leave comments (not spammy, of course -- always make your comments constructive and relevant) on some "nofollow" blogs. Do you only need "dofollow" links? If so, then your blog searching will inevitably be a bit more exhaustive (hopefully, you're using something like the SEOmoz Firefox plug-in to quickly see which sites/blogs are "nofollow"). Although commenting will suffice, one of the best things you could do is ask to guest post on that blog and provide an article based on the topic you're interested in; so, take that into consideration, too.
That pretty much does it for the method I wanted to demonstrate in this post. For your consideration, I've decided to add a few additional tips below that will play well with this method. I hope that you find them useful in correlation with the method above and/or with your other link-building endeavors. Good luck and have fun searching!
Bonus Tip 01: If you do decide to leave a comment on a blog, try submitting that blog's home page and RSS URL to pinging services like Ping-O-Matic and Pingoat. There's no guarantee that the result will be Google's bot revisiting that blog and finding your comment any faster than if you hadn't submitted the blog, but it takes all of 15 seconds each to submit and you very well may be doing yourself a favor by doing so!
Bonus Tip 02: If you are curious as to seeing if/when Google has cached a page with your comment, simply search for that page in Google, click "cached," then look up at the top where it says, "...a snapshot of the page as it appeared on..." The time and date you see will be the most recent cache of that page! If the time and date are later than the time and date you commented, then scroll down and see if your comment was cached along with the page.
Bonus Tip 03: Set up Google Alerts and have Google email you whenever they index a new blog post related to a keyword term you're interested in! Simply visit Google Alerts, put in your keyword term, select "Blogs" from the type selection box, select how often you want to receive results, then select the volume of results you want and enter your email address and you're all set!