10 financial rules of thumb

When it comes to answering perplexing questions about money, you can't go wrong with research. You can diligently study a situation. Ponder alternatives. Consider nuance.

Or you can save yourself a bunch of time and make a pretty good guess.

Just as in other areas of life, in the world of personal finance -- buying a car, saving for retirement, paying down debt -- there are a few rules of thumb. We're not saying they are always true. We're not saying they fit every single situation. But the experts we consulted say they are useful guidelines that can get you where you need to go.

Should I buy or lease a car?

If you're just considering dollars, you're better off buying, said Cynthia Anderson, certified financial planner and chairwoman of the Financial Planning Association of Charlotte. Two exceptions: If you're someone who buys a new car and trades it in every two or three years, leasing may save you money. Second, if you own a small business and will use your car almost entirely for work, leasing can offer tax deductions, Anderson said.

How much life insurance should I buy?

The old rule of thumb was to buy 5 to 10 times your salary. Forget that, said Greg McBride, senior financial analyst at Bankrate.com, an online provider of financial rate and personal finance information. The old guideline, McBride said, doesn't take into account your dependents' financial needs. Instead, ask yourself what your income would cover if you were alive: Braces? Mortgage? Groceries? College?Because this involves estimating future expenses, it's best to try an online calculator such as the one at Bankrate.com. (Go to bankrate.com/brm/insurance-advisers/life-insurance.asp.) In the meantime, you can figure how much you would need just to replace your present-day income. For instance, if your money earns 5 percent in interest, you would need $1 million in insurance to generate $50,000 a year for your dependents.

How big of a mortgage can I really afford?

Lenders still say that your total monthly housing expenses -- mortgage, interest, taxes and insurance -- should be one-third or less of your gross monthly income, said a Wachovia Corp. spokeswoman.

Other experts suggest you ask yourself additional questions, such as: Is my job likely to change soon, and if it does, will I earn less? Do I expect to have a child soon and if so, how will that change my cash flow? Will expected expenses with this home -- energy, renovations, yard maintenance -- tip my cost higher than I can comfortably manage?

Do I take the car rental insurance or no?

Save yourself hand wringing the next time you're at a car rental counter. Check now with your credit card company and your own car insurer to see if they protect you when you're renting a car.For instance, said John Harvey, State Farm agent at the company's Park Road office, if you carry collision and comprehensive insurance on your own car, many insurers extend that to rentals. One caveat: Protections may not apply overseas. But your credit-card coverage often does.

When does it make sense to buy another car instead of repairing the old one?

Tom and Ray Magliozzi, hosts of National Public Radio's "Car Talk" and authors of the syndicated Car Talk column that runs in MoneyWise, say from a purely economic point of view, it's always cheaper to repair your current car than to replace it. The only exception: If the car is badly rusted, it's probably not worth it to attempt a major repair.

How much of my income should I be saving for retirement?

Prepare to be depressed. The old wisdom was to save 15 percent of your gross annual income. Now, make that 18 to 20 percent, said Eric Clark, certified financial planner with Rinehart & Associates in Charlotte. The reason is simple: We are living longer and spending more.

After I retire, how much of my retirement money can I withdraw each year?

Generally, aim to withdraw 4 percent of your retirement fund annually, assuming you earn between 5 to 7 percent interest on it annually, said Ellen Rinaldi, principal investment counseling and research with Vanguard Inc. However, 4 percent may not buy you the lifestyle you want and you may need to supplement that money with additional earnings. That's also true if you're single, because you may have less savings than a couple but face similar expenses (a mortgage payment, for instance).

If I get windfall of cash, should I put it in savings or pay off debt?

Dave Ramsey, Tennessee-based syndicated radio talk show host and author of "The Total Money Makeover," is known to his listeners as the guy who preaches that "debt is dumb." So it may come as a surprise that the anti-debt guru says if you have no savings and carry debt, you should not write a check to Visa, but put the money toward a $1,000 "baby emergency fund." ("Baby" refers to the size of the fund, not that it's for the little ones running around the house.)"The baby emergency fund gives you a cushion to take care of small, unexpected expenses while you are working on getting out of debt," Ramsey wrote in an e-mail response to our question. "Then use the rest to pay off debts. Pay the small debts off first because marking them off the list gets you excited about paying off debt. If there's still some cash left over after you pay off all your debts, then use it to fully fund your (regular) emergency fund."

How much of an emergency savings fund do I need?

Three to six months' worth of living expenses. That's usually the amount of time it takes to find a job, and job loss is usually the reason you need the fund, said Mary Quinn, director of Charlotte Saves, a nonprofit group that helps people save money. Along with the fund, Quinn suggests you create a written list of the only reasons you'll tap it and keep it where you can see it.

When does it make sense to make an extra house payment?

First, be sure your mortgage provider won't charge you a fee to pay ahead. If there's no penalty, make the extra payment only if you don't carry higher-interest debt or can't earn more in interest on your cash by saving it, said Mary Quinn, director of Charlotte Saves.