Many people who set up as consultants never make more than a minimal living. They get some clients who like them, but are so dependent on these few businesses that the resignation of a key contact can destroy their business for months ahead.

The problem? They're nice folks who do a great job and have lots of experience, but they're not indispensable or even memorable. They can be replaced any day by another nice person with, apparently, just as much to offer. Or, more likely, by a new college graduate from a big consulting firm with minimal expertise but the power of the big brand name.

Being THE expert (or at least THE expert in your neck of the woods) is pretty much the only way to fight back effectively.

Here's why. Experts are given things other consultants have to work damned hard to get.

1. Access. Corporate Big Dogs like to feel they're dealing with the top banana. Their staff know they won't be criticized fro letting these people through the defenses around their boss.

2. Trust. People believe what experts say, until they're proved wrong (and sometimes then as well). More trust means less feeling of uncertainty in the buyer.

3. Standardization. Corporations like to have standards for things -- preferably ones that apply industry-wide. They don't like having different approaches to the same problem in every division or department. They want to believe a consultant can set a standard everyone will accept.

4. Validation. Corporations don't like to be trend-setters. It risks too many people's reputations. That means they always want to know if the person they're using has done the same thing successfully before, ideally with a business they see as being like them (or better). This produces a Catch-22 situation where you can't get the validation until you get the work; and you can't get the work...Experts are often immune from this, even if the only validation they have comes from having written THE book or article on the topic. And it doesn't matter how narrow that topic is, so long as it's important to the client.

5. Latitude. Because people trust an expert, they give them more latitude to make mistakes or vary the brief. You can't push this too far, but it does mean clients are more patient in waiting for results. If you're seen only as someone brought in by a specific person (probably because he or she is your friend), you'd better produce instant results or you'll be out on your ear.

6. Credibility. People listen to experts and allow themselves to be persuaded. A lousy, amateurish presentation by an expert will beat a slick, professional one by a non-expert every time. Indeed, the slicker the non-expert's presentation, the more the audience will suspect they're being hoodwinked into buying snake-oil.

If you really want to establish a small consultancy working in a generic area like leadership training, it's a free country. Just don't expect it to be anything other than a bed of nails with an earnings level considerably lower than your neighborhood plumber.

Adrian W. Savage writes for people who want help with the daily dilemmas they face at work. He has contributed more than 25 articles to leading British and American publications and has been featured in The New York Times, The Wall Street Journal, USA Today and The Chicago Tribune.

Visit his blog on the ups and downs of business life.