When it comes to helping your website rank well in the search engines for relevant keyword phrases, there are plenty of on-site best practices that should be on the list of every diligent webmaster.  Meta titles, linking structure, original content, image alt tags and page load time all play a big role in how the search engines rate–and rank–your website.

In spite of the attention that webmasters give to on-site factors, though, the single most effective tactic that you can use to increase your organic search traffic is still smart linkbuilding.  The formula is simple: the more relevant links you have pointing at your domain from other sites, the higher it will rank for your targeted keyword phrases.

If you’re new to off-site SEO, however, the prospect of linkbuilding can be more than a little intimidating.  With so many different options for pursuing links, what are the most effective?  Remember: it isn’t just the sheer number of links that helps your site rank higher for targeted keywords, but also the relevance of the pages that link back to you.

Here are the five methods for link building that I’ve found to be most effective in the years that I’ve spent in search engine optimization.  While they aren’t the only ways to build links back to your website or blog, they have worked best for me on a wide variety of different sites.  Remember: don’t just limit yourself to one linkbuilding strategy, and never stop digging deep for more places online to get good, relevant backlinks!

1.  Article Marketing

Article marketing is used frequently by countless webmasters to build relevant, do-follow links back to domains, but it’s rarely done effectively.  While publishing original articles on marketing sites does create relevant links back to your site, the articles themselves tend to carry very little search engine authority . . . which means that you have to publish a lot of articles in order to make much of a difference.

It also helps if the original articles that you publish are also well-written and helpful to the target audience, since that makes it more likely that they will be picked up and re-published on relevant blogs (creating even more links back to your site from different domains).

In order to have even limited success with article marketing, plan on publishing several articles a month (at least) and linking back to your site’s homepage and an internal page in the resource box.  The article marketing sites that I’ve used the most are Ezine Articles, GoArticles, Article Dashboard, SearchWarp and Articles Base.

2.  Guest Blog Posts

If done correctly, guest blog posts can be the single most powerful off-site SEO tool you have in your linkbuilding arsenal.  The problem is that effective guest blog posting is much more difficult to do than article marketing, link exchanges and directory submissions.  The links that you include back to your own site are generally much higher quality, though, so it’s worth the extra effort.

In order to get content accepted by an influential blogger for a guest post, it needs to be relevant, useful and well-written (unlike articles on article marketing sites).  Don’t be afraid to submit your guest posts to smaller, less popular blogs as well.  One valuable online community that helps you find other bloggers who are interested in guest posters is My Blog Guest.

3.  Relevant Link Exchanges

Notice that I included the word “Relevant” when mentioning link exchanges.  There are some people who say that link exchanges have been rendered ineffective for SEO purposes by the search engines, but this isn’t entirely true.  As long as you exchange links with sites that are relevant to your own–and don’t overdo it–you can still gain a lot of authority with link exchanges.

It’s best to build professional relationships with the webmasters of relevant sites before suggesting a link exchange.  Become active in your niche’s online community by leaving comments, submitting guest posts, interacting with other bloggers, and referring to your own site when it’s helpful to do so.  This will make webmasters much more likely to agree to a suggested link exchange.

4.  Running A Website Contest

Giving away prizes to your site’s regular visitors is a much more effective–and affordable–link building tactic than you might realize.  While giving away cash or prizes in exchange for links is a big no-no with the search engines, you can still effectively use contests to encourage your fans to interact with your site and mention it to their own readers.

Rather than offering a monthly prize to someone who links back to your site, why not make it an entry requirement to simply mention your site somewhere online?  Whether the contest entrants mention your site on their own blog, in their Facebook profiles, or in an online forum, they will still be building your brand recognition . . . and this will inevitably generate links in the long run.

Once you’ve started your own competition, be sure to advertise it on some of the many free online contest forums such as About Blog Contest, Contest Blogger and Lucky Contests (there are dozens of more places to post your contest, as well).  And don’t think that you have to offer up a super-expensive prize in order to get people to take part; even fun trinkets, books and t-shirts can generate user interaction.

5.  Authoritative Directory Submissions

Directory submissions have been a part of the standard SEO link-building package for years, and there are literally thousands of different directories online that will link back to your website for free.  The problem is that these directories have been severely de-valued by the search engines due to linkbuilding abuse.

Still, submitting your site to a limited number of relevant and higher-authority directories is still a good way to start building a profile of backlinks and reinforce your other strategies.  For webmasters who have a linkbuilding budget to work with, it’s always a good idea to spend a few bucks to get your site listed in authoritative directories such as the Yahoo Directory, Business.com, JoeAnt, Best of the Web and Directory Journal.