A Google search for advice on how to choose the right public relations firm turns up more than 2 million results. But a Google search on firing a PR firm turns up 152 million results. Clearly, despite the abundance of advice out there, something’s not working. For every story of the startup turned overnight success following a Mashable mention, there is a horror story about the startup that burned cash on PR and saw no uplift.

If you’re like most entrepreneurs, you’ll turn to your peers for PR advice. But guess what? A lot of what you’ll hear from them really doesn’t matter. Here’s the advice to ignore and the advice to heed.

What doesn’t matter as much as you think it does:

Experience in your specific industry. Domain expertise in a specific industry should not be the most important factor in hiring an agency. It is more important your PR partner have experience solving a similar business problem like how to attract second round investors, how to scale your user base or how to overtake a market leader.

Who they know. In today’s hyper-dynamic media environment, reporters and bloggers change beats and jobs – a lot. Having a specific contact at Venture Beat is meaningless if that writer leaves to develop an app. The criterion you should consider is does the firm know how to find the right reporters and build relationships.

What they promise. If you’re choosing an agency because they promise a specific number of media placements per month, you’re on the wrong track. It’s not that PR shouldn’t be accountable to metrics, it’s that the metrics will depend on you too. A startup that was featured on the front page of USA Today was out of business two days later because it’s back end sales process was flawed. The agency kept delivering media placements when it should have gone quiet.

What really does matter:

Timing. It’s everything. When is the right time to engage an outside agency? Hire a firm too soon and you could burn valuable money and time; too late and you could miss your market opportunity. Yes. PR is that important. Just ask the CEO whose PR campaign generated so much traffic his site crashed –for a month.

If the agency can make you better. Bottom-line, the job of the agency is to make you better – give you capacity and capability to drive awareness among the people who really matter to you. If you can do it without them, you don’t need an agency. If you can’t, look for one that can make you better by bringing their experience, enthusiasm, creativity and elbow grease to the table.

Chemistry. Can you imagine spending time with these people? You need to really like the people you choose, because you will go through ups and downs during the life of the agency relationship, and liking someone goes a long way to having a productive working relationship during challenging moments.

Experience with startups. Startups have very different schedules, workflows and pressures than more established companies with positive cash flow, a full staff and more resources to throw at a problem. Make sure your PR partner has real experience working with startups.

You’ll want to know what startups the agency worked with, what results they achieved on behalf of those companies and what business objectives the agency helped its clients address. An agency’s ability to understand the startup environment is more important than its portfolio of flashy media placements.

Pace. Your agency needs to be able to keep pace with you, pivot when necessary, and embrace your passion to do what it takes to succeed. Do they have clients you can talk to in order to make sure this is true?

Ability to grow. Just as some executives are meant to be founders but not operational leaders, some agencies are adept at launches but aren’t suited to manage after-launch, momentum-building and ongoing communications programs. Depending on what your objectives are and what your budget is, you may want to hire a firm to launch your product only, or perhaps you’ll be better suited to engage with a longer-term partner who can become a trusted counselor over the long term.

Your account team. The classic bait and switch some agencies are known for is sometimes the client’s fault. An agency may have the best of intentions when they bring in the senior guns for the presentation and then once the contract is finalized replace them with junior account staff because the budget is so unexpectedly low. And, sometimes it’s the agency’s MO. What’s important is who is the day-to-day contact. You want someone who has experience in running an account, who knows how to get your attention, who can marshal other agency resources to get the job done efficiently and well.

Flexibility. Too often agencies have “a way” that doesn’t quite fit with yours: they only give reports on Fridays, they use Google Docs and nothing else, they’re not reachable on the weekends. How does the agency map to a client’s procedures, milestones, schedule etc?

You Get What You Pay For

Deciding how much capital to dedicate to an outside resource is a key part in the process. Declare a budget as early in the process as possible. This helps the agency put together plans that are appropriate to the budget available — not present awesome ideas that will put your company at the top of the valuation cycle but cost way beyond your means.

Agencies generally have minimums – from $5K – $40K or more per month plus expenses (expect to pay 10-20% of fee for general expenses) for at least six months to engage. Do the agencies you’re talking to have a good plan for the money? Can they scale up and down with you? Or are they going to just throw the most junior person in the room on the business by themselves so that they don’t eat up senior people’s time on a small budget. Penny foolish leads to disappointment almost every time.

The thing you need to know is that YOU’RE going to MATTER to your agency — regardless of the size of the budget. (Expect to pay some up front; also plan to negotiate equity stakes if you have little cash to spend.)

Finding an Agency

If you’re not going to just hire someone you know, choose four, no more than five, agencies to talk with that can actually work with you, have capacity, don’t have a conflict, and have an appropriate minimum billing requirement for your budget. (You may have to talk with ten to net four to evaluate).

To compare and contrast:

Tell them as much as you can about what you’re trying to accomplish and have them spend some time thinking about the best approach for you.

Meet the team that would work on your business, or at least the day-to-day contact and their boss.

Put their answers and your meeting through the filter we’ve outlined here. Most likely the answer will be a clear choice (or two). If no one floats to the top, don’t hire and re-think your approach.