When it comes to pay-per-click (PPC) advertising, driving positive ROI is every marketer's goal. If you're seeing diminishing returns from your PPC campaign strategy, a number of factors could be causing this negative outcome. Take some time to revisit those campaigns and see if you're making one of these common mistakes.

You're Not Using Long-Tail Keywords

Businesses like Target, Wal-Mart and Best Buy might see big returns from ad campaigns focused on broad, popular keywords like "iPhone" or "laptop," but this type of approach typically isn't useful for small or midsize businesses. Research compiled by eConsultancy found that around 70 percent of search traffic comes from long-tail keywords that are at least four words in length. If you haven't already, it may be time to examine your local market and determine what sort of specific, long-tail keywords people use when searching for your business.

Paid search has plenty to offer small and mid-sized businesses, especially when those brands aren't ranking at the top of their desired keyword searches. But spending for this ad space needs to be carefully done so that you aren't throwing away all your marketing dollars. And even when you find the right bid opportunity, there's more work to be done: You need to have strong ad copy in place to take advantage.

No matter the scale, running a paid search campaign can be demanding, as marketers must find a working balance between different keywords, calls to action and ad copy so the campaign runs efficiently. While it may be tempting to throw out a few split-tests and leave the rest to trial and error, there are concrete things marketers can do to run a balanced campaign that connects with consumers but doesn't break the bank.

Keyword Caution

Finding the right keywords can be a tricky business. You don't want keywords that are too popular, as your paid search campaign will be crowded out by similar businesses selling comparable products. However, pick something too niche, and searchers might not find you.

Just as search engines tweak their algorithms, an SEM campaign strategy needs to adjust accordingly. Google and other search engines continually work on improving algorithms and connecting consumers with the information they seek.

If you follow the rules and keep up with these changing demands, you can use this evolution to your advantage. Here are four crucial reminders for SEM this year:

1. Acquaint Yourself With Schema

Schema is a way of organizing data developed and promoted through Schema.org, and the way it works is simple: If you've ever typed in a Google search result that delivers the answer to a question in a text box above the search results, that's the product of Schema. It uses structured data to give on-page information context that Google uses to seek out simple search query answers, according to Search Engine Watch.

Search engine marketing (SEM) may sound like a simple concept, but with the ever-evolving world of changing algorithms, enhancing search engine results pages and the increasing focus on local and social results, this world has become increasingly complex for even the most experienced marketers to navigate. Fortunately, there are some simple audits for your SEM plan to find out why your strategy isn't working.

Your Keyword Strategy Isn't Good

According to Forbes, recent updates to Google's search engine algorithm have removed the focus from direct keyword matches in 2016. Instead, the search engine giant uses a complex system that determines user intent and attempts to find pages that match broad topics rather than specific words. So, for instance, a consumer who searches for "Pet Care 32837" will get results for grooming salons in Orlando, Florida.

One of the biggest reasons why small and midsize local businesses have shied away from search engine marketing (SEM) in recent years is due to the growth of social media marketing.

Facebook in particular has been a great platform for local businesses, as its programmatic infrastructure is easily scalable to fit almost any budget, and marketers are often already familiar with the platform.

However, though social media has made marketing accessible to the masses, there are a number of reasons not to discount the importance of SEM for local businesses.

Paid search is one of the most effective ways to grow your online business, and call-to-action phrases are one of the most important elements of successful search engine marketing. But search engine results pages (SERPs) are highly competitive arenas. With all these businesses going after the same customers in the same place, it's more important than ever to refine your call-to-action phrases so they're irresistibly clickable.

The Call-to-Action Phrase

The best known call-to-action phrase (CTA) is "Buy Now." But while this may be exactly what you want a visitor to do, it's not a very enticing message. In a search engine marketing (SEM) context, you must consider that when your ad appears, it will appear as one of many others. Design and page placement matter, but the difference between being passed over and actually getting your customer to "Buy Now" lies in the wording of your CTA.

Google AdWords recently announced it will launch a new feature for marketers that allows cross-device targeting campaigns for the first time ever. This means that if someone searches for a company's product or service in the morning on a smartphone, you can then serve ads related to that product on his or her desktop computer at work or tablet on the train ride home.

As long as the potential customer is signed in to a Google account (via Gmail, YouTube or any other Google service), marketers are now able to use powerful tools within AdWords for retargeting. Though it's been a long time coming — Facebook has been leading the way in cross-device targeting for many years now — this new development has some very practical implications for advertisers using Google's AdWord platform.

With over one billion global Gmail users as of February, according to Digital Trends, chances are good that either you or the person sitting next to you is one of those users. And though this free email service is only a decade old, Google has provided an interesting way for advertisers to reach consumers in a place where (according to The Huffington Post) they spend over six hours a day: their inboxes!

What are Gmail ads?

Gmail ads are a specific type of native advertising that uses Google's AdWords platform to target users based on the content of messages in their Gmail accounts. If you've ever used the browser version of Gmail, you may have noticed a "Promotions" tab near the top of the page. This is where they can be found most easily. These ads are formatted like short emails with 25-character headlines and 100-character mini-bodies. Consumers can click anywhere on these lines to view expanded ads that look like emails and typically contain graphics, links, and additional text.

If you do any travel advertising, you know that the days of the white-gloved, bespoke traveler are far gone. It's long been true that travel is booked almost exclusively online — whether through branded travel apps such as Expedia, independently by going directly to hotel and airline websites, or even by travel agents (who, yes, still exist). For businesses that rely on tourism, this has created new opportunities to reach customers.

The Purchase Journey

Long before a trip is booked, consumers begin to research destinations. The purchase journey can run the gamut from daydreaming about what it would be like to stay in the Caribbean to actually investigating the cost of flights, hotel rooms and things to do in Antigua. It is along this path that marketers for hotels, chambers of commerce and travel destinations can reach customers, particularly through search engine marketing (SEM).