Your company’s humming along.

Sales are strong, just about everyone on your team seems busy, and for the limited niche you serve, you’re showing healthy returns on your marketing investments. In other words, there’s only one way your company can go: up.

Except one little thing: you don’t know how to make that happen.

When there’s potential for growth in your niche but your marketing gas tank is empty, it may be time to bring in a marketing agency for your small business. But how do you know which one is the right fit? How do you know if an agency that makes bold promises can live up to them? Let’s look at how to choose — and vet — the right agency for your small business.

Define Your Marketing Goals

Before you search, you have to know what it is that you’re looking for in a marketing agency. It comes down to defining your specific goals. Ask better questions of your potential marketing agency, and you’ll get better answers.

Not sure where to begin? Here are some major variables you need to take into account:

• Budget. Your small business likely isn’t going to hire the same agency that works with a corporate behemoth. And that’s fine. Just know what you’re willing to spend off the bat so you know which agencies — and their subsequent paychecks — are out of your league.

• Strategy. Does a marketing agency understand your niche? Are they capable of targeting your potential customers, or are they focused on completely different media? Is their expertise in traditional marketing whereas you need a modern, Internet-borne lead?

• Return on Investment. How much growth should you expect? If a marketing agency can get you more leads and more publicity, how would that translate to return on your investment? Do you have a sales funnel in place that makes this relatively predictable, or is aggressive growth a little scary?

It doesn’t matter what your marketing goals are now — you just need to define them so you can see which agency matches your needs.

Dig Up a List of Potential Agencies

With your goals defined, you’re ready to dig up a list of potential agencies. Here are a few strategies you can use:

• Searching “marketing agency” + “[your location].” Call this the “phonebook” method of research. It might be dull. It might feel like data entry. But you can find some legitimate agencies through this method — after all, you know they’re on top of their SEO.

• Try directories such as AgencyList. Take any sort of ranking like this with a grain of salt, but consider these resources useful for generating a list of potential agencies in your area.

• Ask for referrals. Through your social media presence or even through your personal network, put out a few feelers and see if there are any marketing agencies that come pre-packaged with a recommendation from a trusted source.

Why so many different strategies? Simple: you likely won’t find your ideal fit with a simple Google search. Choosing and vetting a marketing agency is more like a 5k than a sprint — some agencies may never even respond to your queries. Have patience with the process.

Research the Agency’s Strengths and Experience

Now that you have a list of agencies — and a list of what it is you need out of your marketing agency in the first place — you’re ready to match strength and experience.

When gauging experience, try looking at a few case studies. Do their case studies resemble what you need? In other words, if this was a “before and after” profile, does your company look like the “before”? And would the “after” be worth the investment? If so, that’s a strong indication of a good fit.

You’ll also want a list of effective questions to get at the heart of their strengths, including:

• What’s their strongest area/media? Do they focus on SEO, for example?

• What does their ideal client look like? This is a relevant question from Constant Contact that helps you get an idea of their priorities as well.

• What is their vision for your organization (and does it match up with yours)?

• How many clients stick with them?

• How would they define a sales/marketing funnel in your niche?

• What are the pricing and scheduling terms?

The Critical Question: Focus on Strengths or Shore Up Your Weaknesses?

As you get a better sense of an agency’s strengths, you come to a critical question: is it better to match their strengths with yours, or do you want an agency that will supplement your weaknesses?

This question comes back to your goals — within reason. You don’t want to hire an old school marketing firm that resembles something out of Mad Men if you’re a hip, trendy fashion line catering to millennials. That’s not a match of strength with weakness — it’s just weakness with weakness.

The right “fit” is subjective, but don’t be afraid to go outside the box if a marketing agency has new and bold ideas.

The Vet: Following Up on Research and Previous Clients

After whittling down your choices to two or three options, finish your efforts with a “vet.” This means following up on any loose ends that worry you, or simply research more into each agency’s background to find out more about what it is exactly that they’ll bring to the table.

You can ask for a list of clients or references during the selection process, for example, but keep in mind that they’ll tend to give you their best clients. You can do your own research and ask around with any former clients you’re aware of — a simple well-placed phone call can be the difference between getting suckered in by a great sales presentation or finding the right match for your company.

Decision Time

When it comes to the ultimate decision… well, sorry, but I’ve got nothing for you.

It’s up to you to decide to go with your head or your gut. But if you take the proper steps in researching and vetting a marketing agency, you’ll know how to navigate the onslaught of marketing proposals to get to the heart of what makes an agency right for your business.