Advertising is a $500 billion industry worldwide--and growing--yet many businesses still think they can tackle their marketing needs in-house. But if you're trying to refine your company's messaging and reach your target audience, you should hire an agency that can help position you for growth.

When you're used to overseeing every aspect of your company, handing over some creative control can feel like a big risk, but an agency's expertise and skills can be just what you need to supercharge your company's growth.

Here are a few steps you should take to find the perfect agency partner and avoid the heartache of misaligned expectations.

1. Know what ad agencies do (and don't do).

Many clients think ad agencies sell products. They hire an agency, and if sales don't improve quickly enough, they blame the agency.

However, an ad agency's primary job is to match your product or service with a target audience that needs what you're selling. This can take time, especially in an industry with very long sales cycles.

2. Conduct an RFP.

While not as common as they once were, RFPs allow you to find an agency that matches your company culture and grasps your objectives. During the RFP process, you will not only test the agency's creativity, its understanding of your product, and its media efficiency, but you'll also get to see whether the agency is a good match for your business.

3. Make sure the agency understands your company goals.

Ad agencies work more effectively when they thoroughly understand your target audience, products, company history, competitors, and long-term goals. You can help your agency understand your company better by preparing a proper brief that gives its team focus and clarity.

4. Determine the advertising budget together.

Often, clients ask an agency to determine an advertising budget. Instead, you and your agency should work together to determine industry-standard metrics and compose a budget and workflow that's feasible for both parties. Without reaching an agreement on the amount of time and money required to achieve your goals, your campaign may never get the chance to reach your audience.

5. Know what you want your brand to represent.

Big brands usually appeal to a basic human need to motivate people to buy their products (e.g., sex, self-esteem, fear, etc.). But be careful--the approach your business uses must be consistent with your brand to avoid alienating, confusing, or simply boring your target audience.

For example, Burger King's Subservient Chicken targeted a young audience, but it did not show the product's value or appeal to the brand's focus on family. Initial sales of the sandwich were boosted by a trickle of curious customers, but they eventually plateaued when the launch hype subsided.

Hype doesn't work for long--especially for startups--so you need to ensure your campaign fits your audience and makes sense for your overall brand image.

6. Integrate the campaign across all channels.

The message your campaign communicates should be reflected across all areas of your company, both internally and externally. This means your social media channels, sales materials, customer service dialogues, and even internal communications should support a consistent brand image.

7. Keep innovating.

Agencies can drive prospects, but it's your job to convert them and keep them as customers. You can only retain your customers by continually demonstrating value and growing as a company. Innovation should not end with one campaign; you should always be pushing your brand to evolve.

If you have the capability, hiring an agency is the best way to build your brand and engage with your target audience. There are a few hurdles every business has to overcome when hiring an agency for the first time, but creating unique messaging for your brand and a campaign that resonates with your target market makes it well worth the effort.