If I had to identify the most profitable online marketing strategy available today, I don't think I could come up with a single answer. There are actually three strategies I'd nominate for that honor (in general; every business has unique needs), but separately, they don't have nearly as much power as they do when working all together. In fact, when working together, each strategy influences and encourages the other two to grow, making the most profitable approach less of a single strategy and more of a trinity of strategies working together.

It's easiest to think of these strategies with social media at the center, as it's the most fluid and the hardest to carry out individually. The other two are content marketing and SEO, which some consider to be two sides of the same coin. For the purposes of this article, I'll be treating these three strategies as separate tactics working together.

However you define them semantically, social media affects content marketing and SEO in both direct and indirect ways, and can greatly enhance the overall value of your multifaceted online marketing campaign.

1. Visibility and Traffic

The first benefit is probably the most obvious. The goal of a content marketing campaign is to get more people to your site; people familiar with your content can come back to it, and those who share it can carry its reach to new audiences. But how do you get the initial boost in visibility necessary to earn those shares? If you spend enough time on social media contributing content, reaching out to new followers, and engaging with influencers, you'll build a substantial following, and those followers will happily share your content to outer circles, giving each of your posts that much more visibility (and earning you that much more traffic).

2. Social Signals and SEO

It's actually a myth that social media marketing directly affects SEO. Yes, search sites crawl social media platforms, and your information can be grabbed by indexing sites and directories like Yelp, but there's no direct impact of your social posts on your search rankings, aside from your tweets themselves showing up in branded searches. However, social signals do indirectly come into play. When a user visits one of your pages and shares it on social media, it improves the likelihood that more people will see the page, read it, and, in turn, share it. Done enough times, this activity can lead to inbound links and mentions, which are known to have a direct impact on rankings. Shares themselves are also thought to carry some amount of weight in the search ranking algorithm. While Google has denied this, multiple correlation studies have strongly suggested otherwise. Note that this only applies to on-site shares--retweeted and shared material on social media doesn't share the same impact, since it doesn't require the actual reading of the article.

3. Increased Link Potential

Beyond social shares, social media can indirectly increase your rankings through increased link potential. External links to your domain carry much more authority to your site than basic social signals do, so the more you earn (and the more diverse those links are), the better. It's difficult to earn those links unless you're gunning for them specifically, but social media gives you a tool to get your content in front of thousands--or even more--eyes, all at once. If you write a piece of content entertaining, original, and informative enough to go viral, you could earn dozens or even hundreds of inbound links to boost your content in the search rankings.

4. Mutually Feeding Audiences

Social media and content marketing can share and mutually enhance each other's audiences. For example, the bigger your social media following gets, the more potential readers you'll have for every new content piece you publish. The more active, recurring readers you have for your content marketing campaign, the more people you'll have interested in following your brand for social updates. If you use other mediums of communication, like email marketing, to build and nurture these separate-but-overlapping audiences, you'll stand to benefit even more. Constantly feed your users back and forth by encouraging following in your content and encouraging traffic in your social posts.

5. Content Revival

The investment return potential on content is so great because as long as it's evergreen, it's permanent. It stays on your site and remains valuable theoretically forever. If you have a post that's several months old, don't let it go to waste--use social media to revive it. If you update it with new information, or use it as a response to a user or a citation in a discussion, you'll instantly grant new life to the piece. You could even produce a content syndication schedule to revitalize evergreen posts on a recurring basis.

6. Quality Gauging

Social media also lets you know how well you're doing in the content marketing game, which might otherwise be hard to gauge. How many people visited your site after seeing your content titles? How many people commented on your post, and how many people shared it? Do people prefer one type of content post over another? Are some big hits and others major letdowns? You can use this information to audit, adjust, and reevaluate your content efforts, essentially giving you a platform for continuous self-improvement.

Many new and old-school entrepreneurs treat social media with a degree of skepticism, unsure how posting on Facebook or Twitter could generate any meaningful return on investment (ROI). Skepticism is good, but hopefully by now I've shown you that social media isn't just a self-contained strategy; it's a multi-purpose tool that can enhance and mutually benefit from your other marketing strategies. And when working in harmony, the effects can greatly outweigh your original investments.

Further reading:

The Definitive Guide to Social Media Marketing