Tell me if this sounds familiar: Your marketing department is churning out consistent, high-quality work but generating fewer and fewer leads. Everything seems to have lost its effectiveness. It's actually a common problem.

The root of the issue is that the world often changes faster than our marketing campaigns do. For instance, 16 percent of Americans use ad blockers when browsing the internet on their phones via Firefox. If you think you can get around that with a sophisticated inbound marketing campaign, consider that the average person reads an article or a blog post for all of 37 seconds before flitting to something else. (If you're still with me, congratulations. You're above average.)

Thankfully, there's a straightforward solution to this problem. No, you don't need to fire your whole marketing team. You just need a fresh injection of outside ideas. And don't worry, that's not as hard -- or as expensive -- as you might think.

1. Augment your proprietary data with "outside insights."

Knowing how customers respond to your marketing campaigns is valuable, but it's not the whole picture. It can't tell you whether something you didn't try might work better, for example, and it's only backward-looking.

In his new book "Outside Insight: Navigating a World Drowning in Data," marketing data expert Jørn Lyseggen, CEO of Meltwater, says that "running a company based on internal data alone is like driving a car looking in the rearview mirror."

Lyseggen reminds us that our customers' and competitors' digital footprints are everywhere, and they can offer valuable predictive insights to anyone with the time and inclination to look. "Companies use their website to share the latest positive updates with their clients," Lyseggen writes. "In the process, they also inadvertently broadcast that information to competitors and suppliers."

2. Inject new ideas into your design campaigns.

This step would have been much harder even a decade ago, but with the growth of contract workers and the sharing economy, it has become simple to bring in highly qualified creative talent on an as-needed basis.

A good place to look is the global talent pool at Working Not Working. This invitation-only site features top-performing creatives available for one-off freelance gigs, temp assignments, or even full-time work. Its areas include advertising, design, technology, production, photography, and animation. The site has supplied talent to companies such as Apple, Google, Facebook, and The New York Times.

3. Survey dissatisfied customers.

Businesspeople might have a reputation for being a bunch of data-driven analytics, but we're human like anyone else. And a consistent human foible is confirmation bias. We don't like to hear that we're wrong, so we often ignore or avoid situations that might challenge the decisions we've made.

In business, this means we look for evidence that what we're doing is working. We look for ways to measure our success. But if your marketing campaign needs improvement, you're going to have to look elsewhere. You need to look at how you're failing.

There are some good text analytics tools out there. One of the best is OdinText, which uses patented technology to quickly and accurately crunch large data sets to measure consumer sentiment. Analyze the customers who were dissatisfied with the customer experience and the ones who wouldn't recommend you to others. Determine which issues they're talking about more frequently than your satisfied customers are. Some of these issues might not be solvable in the short term, but others might be easily addressed by your creatives.

4. Cross-train your employees.

Not every company has the budget to hire consultants or freelancers, but anyone can refresh current employees through cross-training.

Similar to the fitness craze, cross-training at work involves stretching and building different muscles -- creative muscles. A web designer will try her hand at copywriting. A project manager will try photography. It's not prescriptive. Give them time to explore, and they'll bring a fresh perspective to their own work.

You likely won't be able to grant employees 20 percent of their work hours to pursue these creative projects as Google once did, but if you can generate a fraction of the good ideas Google garnered from the practice (such as Google News, Gmail, and AdSense), you'll be far ahead.

The business environment is highly adaptive. Don't get caught up in the specific tools that produce fresh results today -- they'll spit out stale results tomorrow. Pay attention to the processes that lead to fresh thinking, and then rinse and repeat.