While it’s hard to put an exact figure on how much elder financial abuse costs older Americans — in part because much of it goes unreported — estimates range widely from $2.9 billion to $36.5 billion annually.

What’s more, large numbers of older people are unaware of some of the common scams that swindlers use on them, according to data released Thursday by AIG Life & Retirement. And that’s something that Michele Kryger, head of AIG’s Elder and Vulnerable Client Care unit, says is a problem.

“It’s important to know about these common scams and the red flags,” she tells MarketWatch, adding that knowledge of the scams can be a first defense against them. (Of course, it’s important to point out that if you have a family member with cognitive decline like Alzheimer’s or dementia, simply being aware of the scams might not be enough to prevent them getting defrauded.)

Some of the scams that more than half of older Americans aren’t unaware of, according to AIG’s research, include invoice scams, prepaid credit/debit card scams, romance scams and the “pigeon drop” scam.

The invoice scam is when the “victim is contacted by someone claiming to work on behalf of a company such as a utility to collect fees,” AIG explains. The romance scam is where a victim is wooed romantically online and then asked for money, and the prepaid credit card/debit card scam is when “the victim is asked to make payments to a utility or other company to address a debt,” AIG says. Finally, the pigeon drop scam is when the “victim is told that a considerable sum of money was found and will be shared with them if an upfront payment is received.”

On the plus side, there are other scams that most older people are aware of, including lottery scams (where swindlers claim you’ve won the lottery), IRS scams (where they pretend to be the government and claim you owe back taxes), charity scams (where they pretend to be a charity to get you to donate) and more.

While many of us think we won’t be the ones to get defrauded, experts say these criminals are getting more savvy. So how can you protect yourself?

One huge red flag, says AIG’s Kryger, is “anytime someone is asking you to pay for something urgently” and/or with a prepaid debit or credit card or money order. In these — and plenty of other — instances, “don’t make a payment over the phone” or via email, she says. Instead, hang up or get off the email, go on the company’s website and look for the phone number of the company there; call that number directly and ask about the issue.

You should also avoid picking up the phone for any number you don’t recognize (even if it seems familiar-ish) and don’t give any personal information like your Social Security number or credit card number over the phone or on email.

And even if an email from a company seems legitimate, beware, as I recently reported: “Fraudsters often set up websites that look real but may be fronts to sell you stolen goods and steal your credit card information.” For example, if a retailer’s name was Hill and its legitimate site was Hill.com, the fraudulent site might add an “s” to the end of that. If you’re not sure if a site is real, here’s a browser extension that can give you an overview of a site, as well as reviews and traffic. Finally, check out this resource from the Justice Department that details common elder financial fraud scans and how to protect yourself.

Worried that you might have been defrauded despite all your precautions? Check your bank accounts and credit and debit card accounts for any suspicious activity. Also, look at your credit reports (you get one free each year from each credit agency by going to AnnualCreditReport.com) and use sites like WalletHub and Credit Karma, which now offer free credit report monitoring, to get alerts when there are changes on your credit reports.

“With people living as many as four decades in retirement, it’s paramount to safeguard hard-earned savings against scams and exploitation,” Kryger says.