The 7 new rules of financial security

Old thinking: Borrowing sensibly is a good way to build wealth.
New rule: Borrow cautiously. You have to worry about the other guy's debt too.

The quarter-century leading up to 2007 wasn't simply a golden age for stocks. It was also a bull market for leverage. (That's Wall Streetspeak for debt.) Since 1982, mortgage rates have fallen from 16% to below 6%. The levy on college loans dropped to around 3%. Americans responded to easy credit in a predictable way. The personal savings rate fell from over 12% to zilch, and household debt payments as a percentage of disposable income rose by a third as families "put it on the card" and paid for lavish kitchen upgrades with home-equity loans.

Looking back, America's borrowing binge was nuts. Families were leaning on housing wealth, and that wealth was shaky.

The obvious moral here is to be conservative. There are always good reasons to borrow, even today. You need a mortgage to buy a house, and a college education provides enough of a lifetime payoff to justify a loan. But you ought to stretch less.

There's a subtler lesson too. David Ellison, president of the FBR Funds, says that you have more exposure to leverage than you think, especially now that everyone is trying to unload debt. Perhaps your employer borrowed a lot over the past decade and now needs to conserve cash, so it's laying off staff. Suddenly that HELOC you could easily handle on your salary doesn't look like such a super idea. You can't lean on your investments for help, because many of the companies you owned used leverage to pump up profits, and now they can't borrow, so their earnings and stock prices are falling. And it's harder to shore up your own balance sheet by selling your house when banks are reining in lending and potential buyers are scared to borrow for an asset that may decline further.

What to do: Be conservative about debt? Make that very conservative. Especially when your neighbors aren't. Get a mortgage you can afford for the life of the loan, and put at least 20% down.

NEXT: Rule No. 5: Housing