The data piles up. Everything your business does must be recorded and dumped into a database so it can be leveraged for decision making and analysis down the line. What happens when the loads of data get too big for you to handle on your own? It could be time to get outside help.

The Data Warehousing Institute offers analysis and advice on various aspects of data warehousing, including working with consultants. The firm estimates there are more than 1,000 consultants working in this space. How do you know who to work with? The choices are almost overwhelming. While some consulting firms offer a range of data warehousing services, others specialize in project management, project methodology specific to data warehousing, information architecture, data acquisition techniques, technology selections, or tool implementation.

TDWI gathered the insight of several industry experts to answer this question. If your company is going through the process of selecting a data warehousing consultant, TDWI advises that you avoid these common mistakes:

Hiring a "doormat" -- As TDWI explains, successful companies work with a consultant with the skills and courage to challenge them. The key is to find a partner who is intelligent without being arrogant. Work with someone who is professional but not afraid to express views and methods different from yours. Doing so will give you access to experience and skills not normally available to you. In the end, you'll do better with someone who can respectfully suggest new ideas than you will with someone who never raises an objection.

Using only half your brain -- Use both analytical and intuitive decision making when selecting a consultant. Consider a number of partners for the multiple parts of the data warehousing project. Avoid using only consultants that you already know.

Making a long-term commitment too soon -- If you can, work with the consultant on a short-term basis before making a long-term commitment. To help your organization overcome any uneasiness in working with outsiders, use trial service packages. This will let you see the consultant in action firsthand.

Terminating a consultant too quickly -- Have a process for early and regular feedback. If you're unhappy about something, communicate about it immediately. When examining problems, consider your original goals and changes in the situation: Is the problem consultant performance or changes in expectations? Determine and agree on actions that will fix the problem.

Thinking that "one size fits all" -- Your needs are unique, and you have the right to demand a customized approach. To get maximum results for your budget, combine the expertise of high-price consultants with the experience of less expensive consultants. Don't try to find one person to do everything.

Holding unrealistic expectations -- Be realistic about what you want and what the consultant can actually deliver. Do not assume the consultant will solve a host of cultural, political, and technical problems on its own.

Discounting your team -- Involve your own team members in the selection process right from the start, communicating to them the purpose, benefits, and expectations for hiring a consultant to assist in the data warehousing project. Your employees/coworkers will be more likely to buy into the project and cooperate.

Giving up too much control -- You're the one at risk here -- don't give up too much authority. A good consultant will complement an operation, not take over. Management is ultimately accountable, so it should maintain control and share in decision making. As TWDI puts it, "A good consultant is no substitute for a good leader."

Settling for less than you expected -- When selecting a consultant, be sure who you see is who you will get. Talk to the person before getting started. You should get the expertise and knowledge you pay for.

Overlooking personal integrity -- Written contracts, penalties, and legal remedies don't provide a guaranteed solution to all the "gray" issues that can come up every day. For both parties, personal integrity is the only way to make sure everyone lives up to expectations.