如何Hire the Right Google AdWords Ad AgencyBy asking the ad agencies these 11 questions, you should be able to find one that's a good fit for your business.

In their bookUltimate Guide to Google AdWords, online advertising and Google AdWords experts Perry Marshall, Mike Rhodes and Bryan Todd offer information thatwill help you get more clicks from Google for less money, convert more visitors to buyers, and make your online business more effective than ever.In this edited excerpt, the authors explain exactly what you should be looking for in an agency to help with your AdWords campaigns.

If you're trying to hire an ad agency to help you with your Google AdWords campaign, don't bring any firm on board until you've done your homework. While some of the following questions carry more weight than others, none of them are trivial. See how many of these you can answer by researching the websites of the agencies you've shortlisted. After that, speak to each agency directly to obtain answers to everything else.

1. Did the person who's going to be managing your AdWords account learn AdWords on their own dime?This is the acid test for account managers. There's something about learning to make your Google campaign profitable using your own money that makes you get smart faster than anything else. Your mistakes are directly painful, and you never forget the lessons you learn.

This is in stark contrast to the employee who's guaranteed three square meals a day regardless of whether the traffic converts or not. The two aren't even remotely comparable.

If you're going to hire an agency (or employee or contractor) to manage your campaigns, ask them to prove to you that they built a successful, profitable campaign with their own money. The next best thing after that is the contractor, employer or agency who learned on someone else's dime but was incentivized by commissions to make the campaigns successful. Again, they need to prove to you that they made campaigns hit pay dirt.

2. Is the agency really an agency orjust a one-man band? You want an agency with lots of resources, lots of experience and lots of personnel. You don't want your AdWords account to be neglected because your lone worker has gone on holiday or come down with the flu.

Now mind you, there are experts who work solo, without a big staff around them. They know AdWords inside and out, and network closely with other experts in making strategic decisions. But they're an exception to this rule.

3. What services does the agency offer?The best answer? They specialize in pay-per-click (PPC) and little else. If they also offer search engine optimization (SEO), social media, web design, print fulfillment and lots more, this is a red flag. Some multiservice companies will say that they offer PPC when it's really only a sideline.

If you need knee surgery, you don't go to a general practitioner or a heart doctor. You get a specialist. PPC campaigns are no different. You're looking for stone-cold, PPC-obsessed professionals.

4. How did you hear about the agency?The absolute best circumstances under which to hire an agency are:

1. A trusted colleague recommended the firm to you, or

2. You heard one of the agency's senior managers give a brilliant talk at an event.

Always get references or case studies from previous or current customers.

If you hire an agency that contacted you out of the blue by email or by cold calling, without you seeking them out first, what does it mean? A firm like that usually has other priorities—they may be more focused on grabbing market share than on doing a high-quality job for you the client.

5. Have they worked with anyone else in your specific market or vertical niche?If not, it isn't a deal-breaker. But it's a good sign if they have prior experience in your sector. Every niche has its own idiosyncrasies.

6. How do they report their results?The first answer you're looking for is: They'll connect your AdWords and Analytics accounts and will always report your AdWords results in the context of your other traffic data.

Beyond that, you need to know what kind of reporting cycle they have and the format in which they'll deliver it. They should provide what you need—weekly, monthly, quarterly, annually and anything in between!

7. What key performance indicators (KPIs) do they use?Bad agencies talk about number of impressions, number of clicks, clickthrough rates or even the position of your ads. Good agencies talk about cost per actions, volume of conversions, and profit.

8. What account management system do they use?Agencies may hold back specifics in the early stages of their discussions with you. That's not unusual. The important thing is to know they have a system and that they don't just manage accounts on an ad hoc basis.

9. Who exactly will be working on your account?Once the relationship begins, your account is managed by one or more highly trained PPC expert. Don't be afraid to ask for specifics about the people who'll be physically working on your account. Even better if you can meet them in person.

10. Is the agency certified?It should be at least AdWords certified and part of the Google Partners™ program. Don't be fooled into thinking this automatically gives the agency legitimacy; certification requires passing a few fairly easy exams, as well as maintaining a minimum monthly AdWords spend of $10,000—which is a fairly low bar in the scheme of things. If an agency doesn't even have Google certification, you're dealing with amateurs.

11. What does your gut tell you?Don't be horrified by this question. PPC isn't an exact science. There's always a level of artistry that goes into the equation. Similarly, choosing an agency can't be made solely on cold, hard facts.

Continue to talk to the agency until you feel comfortable with your choice, whether it's to hire them or look elsewhere. The right agency will talk the talk, have good business sense, communicate without using impenetrable jargon, understand the important elements of your business, and have an in-depth knowledge of the AdWords machine.

If you have positive answers to the first of the above nine questions, and you instinctively feel that the agency understands you and your business and what you're trying to achieve, you might just have found your winner.