At a recent panel discussion on financial literacy at Boston University, John Gannon quickly grabbed our attention. He remarked that the personal finance industry focuses a lot on stock and bond market losses, but those losses are often dwarfed by the cost of an investment scam. Fall prey to one and almost all your money disappears. (He said something to that effect; I’m relying on memory.)

Gannon is the senior vice president for investor education at FINRA. The Financial Industry Regulatory Authority oversees securities firms doing business in the U.S.

There’s no shortage of scams. Pump-and-dump swindles. Ponzi schemes. Foreign lotteries. Telemarketing snake oil. Sad to say, there are plenty more cons to name. Gannon offers up some money-preserving advice.

John Gannon We’ve all heard the timeless admonition “If it sounds too good to be true, it probably is”–great advice, but the trick is figuring out when “good” becomes “too good.” There’s no bright line. Investment fraudsters make their living by making sure the deals they tout appear both good and true.

They’re masters of persuasion, tailoring their pitches to match the psychological profiles of their targets. They look for your Achilles heel by asking seemingly benign questions–about your health, family, political views, hobbies, or prior employers. Once they know which buttons to push, they’ll bombard you with a flurry of influence tactics, which can leave even the savviest person in a haze.

Some of the most common tactics include:

The “Phantom Riches” Tactic–dangling the prospect of wealth, enticing you with something you want but can’t have. “These gas wells are guaranteed to produce $6,800 a month in income.”

The “Source Credibility” Tactic–trying to build credibility by claiming to be with a reputable firm or to have a special credential or experience. “Believe me, as a senior vice president of XYZ Firm, I would never sell an investment that doesn’t produce.”

The “Social Consensus” Tactic–leading you to believe that other savvy investors have already invested. “This is how ___ got his start. I know it’s a lot of money, but I’m in–and so are my mom and half her church–and it’s worth every dime.”

The “Reciprocity” Tactic–offering to do a small favor for you in return for a big favor. “I’ll give you a break on my commission if you buy now–half off.”

The “Scarcity” Tactic–creating a false sense of urgency by claiming limited supply. “There are only a few hundred shares left, so I’d sign today if I were you.”

Understanding these psychological tactics and how they can be used against you can help you avoid becoming a con artist’s next victim. And here are three key strategies you can use to protect yourself:

1. End the conversation. Have a refusal script.

2. Turn the tables and ask questions.

3. Talk to someone first. Get a second opinion