What's the No. 1 way to tell that a credit-repair firm is not legitimate? It asks you to pay upfront for services that haven't been rendered, "Blunt Money" says.

Another tip-off, she writes: No matter what they claim, "no one can remove accurate negative information from anyone's credit report."

Unfortunately, many desperate people have responded to ads containing bogus claims, often paying hundreds or thousands of dollars to shady firms promising to improve their bad credit. As a result, the Federal Trade Commission and 22 states have launched a crackdown on unlawful practices, targeting 33 companies.

To read more about Operation Clean Sweep, click here. The FTC also gives warning signs and suggests you avoid companies that:

• Ask for payment in advance. That's illegal.

• Don't explain your legal rights and what you can do to fix your own credit for free.

• Tell you not to contact the credit bureaus directly.

• Tell you to dispute everything in your credit reports.

• Advise you to create a new credit identity by applying for an employer identification number. This also is illegal.

If you want to improve your bad credit, why pay someone? Most likely you can do it yourself.

For starters, get free copies of your credit reports from AnnualCreditReport.com. Avoid other Web sites that are trying to sell you a service.

If you think inaccurate information appears on your credit reports, read this excellent FTC guide about how to dispute it. It even includes a sample letter to send to the credit reporting bureaus.

If you're the cause of your bad credit, Blunt Money says, "the only real way to fix it is to change your behavior and give it time." Pay your bills in a timely fashion, stay well below your credit limits, and work out a repayment plan with creditors if you've fallen behind.

If you think you really need help, the FTC advises how to find a legitimate credit counselor.

If you believe you've been scammed by a company offering credit repair, you can file a complaint at www.ftc.gov or by calling (877) FTC-HELP.