T+L’s personal finance columnist, Jean Chatzky, answers your questions. This month: A world tour how-to.

Q: With our children off on their own next summer, my husband and I are thinking of taking an around-the-world tour. But we have no idea how to buy tickets. Any suggestions?—D. Schneider, Palo Alto, Calif.

A: What better way to mark a big milestone like a birthday, anniversary, or rediscovered independence than to see all the parts of the globe on your wish list in one go. And while buying an around-the-world ticket isn't as simple as visiting Orbitz or Expedia, it's not as complicated as you might imagine, or as expensive—the average ticket starts at $1,800 for a coach seat. And you don't need to follow a preset itinerary to get the lowest advertised rates. If you see an offer citing eight specific cities, don't feel that you have to settle on those locations. "It's like putting together a puzzle," says Donovan Pacholl, director of marketing for BootsNAll Travel Network (www.bootsnall.com), an online hub for around-the-world travel information. "You start at the perimeter and work your way in." No matter how you piece it together, there are three basic ways to purchase this kind of ticket.

Buy through the airlines and their alliances. You can't fly around the world on a single airline—there isn't any one that serves all destinations. So airlines have formed alliances (StarAlliance.com, OneWorld.com, and SkyTeam.com are the biggies), from which you can buy a ticket that suits your itinerary. This method might not get you the best coach fare, but you can find good deals on business class. And having an alliance on your side ensures good customer service and flexibility, which you'll want when traveling the world. You'll set an initial itinerary, but somewhere along the way you might decide that you love Santorini (and want three more nights) or hate Santorini (and want to get out of there immediately). If you're on an alliance ticket, it's usually possible to change dates for a moderate fee (or even none at all), as long as there's room on the flight. That doesn't mean there won't be restrictions—alliance fares often either allow only a certain number of miles or stops or dictate whether or not you can double-back through a particular hub, such as Bangkok.

Buy discount tickets from a consolidator. Online travel agencies such as Air Brokers International, Inc. (www.airbrokers.com), Airtreks (www.airtreks.com), and Circle the Planet (www.circletheplanet.net) specialize in multidestinational and around-the-world travel. The companies buy plane tickets in bulk (to get discount fares), then package them according to a customer's preferred route. Because these agencies have the ability to draw even from regional airlines, they can put you on a route that's not only cheaper, but also more direct, explains Edward Hasbrouck, author of The Practical Nomad: How to Travel Around the World. Going through one of these consolidators is the way you're likely to get the best price, although flexibility may be a problem. "The cheapest tickets often have the highest change fees," notes Hasbrouck. So make sure you ask about potential fees or penalties before purchasing your ticket. "Remember, price isn't everything," he says. "If you think you'll need to change dates en route, it may be worth your while to be on an airline that serves that destination every day rather than once a week."

Buy tickets as you go. Purchasing tickets on the road is, without a doubt, the most expensive way to travel. You lose the ability to buy in bulk or in advance. But opting for this method will give you the most flexibility. For that reason, some travelers with well-padded pockets prefer it.

Buy with timing in mind. No matter which way you choose to purchase your ticket, there are a few points to consider. You can buy these tickets up to a year in advance. The earlier you buy them, the better the price you'll get. Steer clear of the Christmas-New Year's period if at all possible; prices can be twice as high then as they are during the rest of the year. And let the airlines or travel agencies work their magic for you. Tell them the places you want to go and let them suggest the order of your stops. Finally, remember this as you maneuver your way toward a good fare: the airline tickets are only a part—often, a small part—of what you'll pay for a once-in-a-lifetime journey like this. Don't cut corners—traveling in an uncomfortable way or skipping places you really want to see—just to save a few bucks. After all, you'll probably only make this trip once, so it pays to do it right.

Ask Jean! Send your queries about value-related travel issues to AskJean@aexp.com. We regret that questions can be answered only in the column.