So-called specialized law firms are sending invitations to homeowners for "mass joinder" lawsuits against their mortgage lender, touting it as a way to stop foreclosure and get good loan modifications. The invites are often a scam, says the Federal Trade Commission.

The law firms generally don't deliver, reports the FTC, which also says that many of the firms fail to use qualified attorneys or even pursue cases, and often leave their clients in worse financial shape than before. The firms charge fees in advance that can range from a couple thousand dollars to more than $10,000.

You can guard yourself against all sorts of mortgage scams. Here are some ways to protect yourself:

• Never deal with anyone who charges for help. You can get free assistance from a government-approved counselor by calling 888-995-4673.
  
• Beware of anyone who wants you to sign papers immediately. Never sign over the deed to your home.
  
• Never make your mortgage payment to anyone other than your mortgage company without the lender's approval.

If you choose to take legal action against your lender, the FTC recommends that you: Get the name of the lawyers who will represent you and check them out with your state bar association. Are they licensed in your state? Have they been subject to any disciplinary actions? Also ask relatives, friends, and others you trust for the name of an attorney with a proven record of getting help for homeowners facing foreclosure. Ask to speak with the attorney directly. For more tips from the FTC click here.

For information on what would make you a good candidate for refinancing, and whether to cut your monthly payments or accelerate your home's payoff, see Refinance your mortgage (again)?

Previously: Beware of mortgage rescue scams masquerading as new federal programs

FTC Consumer Alert: Mass Joinder Lawsuits [FTC]