When it comes to your search engine marketing (SEM) strategy, choosing the right keywords can make or break a campaign. From the content you create to the ads you publish, every asset should center around a core list of keywords that align with your target audience's needs.

Whether you're new to running SEM campaigns or consider yourself a seasoned pro, you've likely spent a great deal of time considering what keywords will drive the most clicks and conversions. But what about negative keywords? That is, the keywords you don't want to rank for.

Let's take a look at how a negative keyword list can help improve the success of your SEM efforts.

Millennials' preferences and online habits have affected multiple industries in recent years, but even these disruptive web users will need to buy a car at some point. And you'd better believe that when they do, they're going to do their homework first.

J.D. Power's U.S. New Autoshopper Study showed that customers who use services like Uber, Airbnb and Netflix — considered "disruptive web users" for their preference of web-based platforms over traditional services — tend to spend significantly more time researching cars when shopping. This audience is bigger than you may think, accounting for about 33 percent of Generation Y and 18 percent of Generation X, as well as 6 percent of Boomers and those older than them. Before making a purchase, these individuals visit as many as 12 websites, whereas traditional shoppers typically visit nine.

Marketers know the importance of choosing the right keywords, selecting relevant audience filters and building a landing page that turns referrals into conversions. But if you're serious about PPC campaign optimization, then you also have to spend time hammering away at your campaign's ad copy.

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.