4. Reality Check

Any executive who leaves an office job can call himself a consultant. That's why reference checks are key. Find out if your prospective consultant belongs to a professional organization or is a certified professional consultant.

Ask for and evaluate other recent client success stories that are similar to your goals. Be a little nosy.

"Find someone who has already been there so [the consultants] are not reinventing the wheel on your dollar," says Bartoschek. A big firm might have a great reputation, but it's a good idea to check the track record of individuals who might be assigned to your team.

Bartoshek also advises against the one-size-fits-all approach. "I don't recommend a generalist," he says. "It's very rare to find an expert in a lot of fields. You wouldn't go to the same doctor to pull your teeth and cure your spine."

Hiring consultants with specific technical expertise, such as Oracle or PeopleSoft skills, poses a clear advantage, since they're proven experts in that field. Similarly, graduates of certification programs such as Microsoft's have concrete benchmarks that prove they can do what they advertise.

There are more than 2 million consultants in the United States alone, so how do you choose?

Consultant referral services on the Internet are a good place to start when looking for smaller firms or independents.

National Consultant Referrals is a free service that runs reference checks and includes evaluations of its searchable database of consultants. The Consultants Alley has referrals to International Guild of Professional Consultants members in every category from business to human resources.

The Washington, D.C. - based Institute of Management Consultants, a professional association with 25 chapters across the country, has an online directory of consultants, and the New York-based Association of Management Consultant Firms has a referral system and member profiles of its clients, including big names such as Deloitte Consulting and Ernst & Young.

Third-party evaluators like Gartner Group, Forrester Research, and Meta Group evaluate trends in the consulting industry and can help you make a choice. They typically produce and sell regular reports on trends in the industry and often rank the top players.

If you're looking for expertise in a particular service, like SAP or PeopleSoft, go straight to vendors for recommendations on their best partners in that field. If you really want to comparison shop, attend a professional conference that covers the type of services you're interested in, such as an Oracle developers conference.

Of course, flawless credentials are meaningless if you and a consultant just don't like each other. Meet the individual or consulting team and ask lots of questions. For example, will they be using subcontractors? If so, which ones? Make sure you can agree on a set of deliverables before you start. Don't wind up like the global manufacturing company that hired consultants to put in a new HR system that didn't quite work - costing the firm $100 million.

Have your in-house counsel draft a contract that addresses the terms of acceptance, a schedule of milestones, acceptance and revision guidelines, and noncompetition provisions. It should also cover intellectual property rights, which is a key issue these days, especially for people doing work for hire. Also cover the payment process-some consultants get paid up front, while others work on a pay schedule that is contingent on work delivered. Add communication guidelines, such as how often you'll expect an update and whom the consultant should report to.