First of all, submit to directories that review submissions before accepting them. The whole premise upon which modern search engines are built is that a link from one website to another is an editorial vote as to the quality of that website.
Aside: Several people who’ve read this have written to ask me questions regarding directories. While I’m glad to lend a hand, you should also consider buying an hour of my time. You’ll get to ask me as many questions as you can fit in to the hour, and I’ll give you the answers you need to improve your SEO.
Directories that manually review submissions before including them are the perfect example of this theory. Human editors ensure that only those sites that meet certain standards are included, and thus vote, vouch, or whatever other terms you like, for the website.
Google engineer Matt Cutts recently suggested criteria by which to judge a directory’s quality.
“When considering submitting to a directory, I’d ask questions like:
– Does the directory reject urls? If every url passes a review, the directory gets closer to just a list of links or a free-for-all link site. (http://en.wikipedia.org/wiki/Link_farm)
– What is the quality of urls in the directory? Suppose a site rejects 25% of submissions, but the urls that are accepted/listed are still quite low-quality or spammy. That doesn’t speak well to the quality of the directory.
– If there is a fee, what’s the purpose of the fee? For a high-quality directory, the fee is primarily for the time/effort for someone to do a genuine evaluation of a url or site.
Those are a few factors I’d consider. If you put on your user hat and ask ‘Does this seem like a high-quality directory to me?’ you can usually get a pretty good sense as well, or ask a few friends for their take on a particular directory.”
Second, submit to directories from which you expect to get quality traffic that might buy your products or services. Generally speaking, this means the biggest general directories as well as the smaller industry-specific directories. Some directories are combined with vertical search engines, and these should also be considered. For example, Business.com is both a vertical search engine (i.e. for business websites) and a directory.
Some good directories to submit to are the Yahoo directory (dir.yahoo.com), Business.com, Best of the Web (BOTW.org), and JoeAnt. Depending on the nature of your business, internet yellow pages and online local directories might be a good idea too.