Back in your grandfather's day, folks didn't have to worry about the ins and outs of mutual funds, adjustable rate mortgages, and credit cards. Such options simply weren't available, so when people wanted to buy something — a car, a house, furniture — they saved for it. Not so today. In today's microwave, fast food, gotta-have-it-now society, credit cards are widely available and widely used. Though credit (especially for larger purchases) is not as readily available as it was a few years back, many people still find at least one credit card offer a week in their mailbox.

If you choose to open that envelope, fill out the application form, and carry that little plastic card in your purse or wallet, it pays to be careful. Here are three simple guidelines for using credit cards wisely.

• Don't just pay the minimum. You've heard this before. You go on a spending spree and charge $2,500 for a new wardrobe. If you make only minimum payments, you could take up to eight years to pay off your balance. If the credit card company charges an annual rate of 16%, you'll have racked up over $1,800 in interest charges. A good deal? Yes, for the card issuer. To avoid this pitfall, pay off as much as you can afford every month and don't use your card again until the balance is paid off.
• Avoid cash withdrawals. When withdrawing money from an automated teller machine, pull out your debit or ATM card. Using a credit card to get cash (also known as a cash advance) is a bad idea. Interest rates on such advances are typically higher than rates for purchases, sometimes several percentage points higher. The same holds true for those offers of "free money" in the mail. ("Just sign this check and the money's yours.") In reality, such checks are loans with high interest rates. A good place for such offers is the shredding machine.
• Don't overspend. Many studies have shown that people tend to spend more when using credit cards than when paying with cash. So be careful. If you can't really afford that big screen television this month, do the prudent thing and save for it.

We can't turn back the clock to our grandfather's era. But we can learn from him to cultivate wise spending habits, especially when using credit cards.