Over half (52%) of small businesses in the US invested in search engine optimization in 2016, and 74% expect to do so in 2017, according to new research from Clutch, a leading B2B research and reviews firm. In addition, 66% of small businesses say they plan to invest in pay-per-click digital advertising, such as Google search ads, by the end of 2017.

But despite this increased adoption of SEO as a digital marketing tactic, there is still a great deal of opportunity for small businesses to become more comprehensive in their search marketing strategies. Over 50% limit their SEO activities to local and on-site optimization compared to other initiatives such as content creation or guest posting.

"A comprehensive SEO strategy involves a multitude of disciplines including technical SEO, on-page optimization, outreach and content creation," said Stephen Jeske, Senior Content Strategist for CanIRank, an SEO software vendor.

The survey indicates that external factors, particularly the resources used, tend to dictate the extent of small business SEO efforts. For example, 60% of small businesses currently use in-house resources to develop SEO, rather than external resources such as freelancers, consultants, agency(s) or SEO software and tools.

Experts agree that it is often a combination of internal and external resources that can be most effective for a small business' SEO efforts.

"The in-house person eventually gets to a point where they hit their limits. They don't have the training," said John Lincoln, CEO of Ignite Visibility. "To do SEO correctly and really compete in this very competitive online space, it's good to have a true external expert that's working at an expert company along with somebody who's in-house."

In fact, small businesses that use a combination of in-house and external resources exhibit the most comprehensive SEO strategies. Specifically, they are more likely to invest in local and on-site optimization, create content, and to guest post, compared to small businesses that only use in-house resources, the study found.

Based on this research, Clutch identifies three action items small businesses can implement to strengthen their SEO strategies, including expanding which metrics they track and activities they pursue, prioritizing the creation of content assets, and using a combination of in-house and external resources for SEO.