Watch the Video on Losing Your Wallet

If you're divorced and plan to travel out of the country with your children, check the legal requirements in advance. When I tried to take my kids to Cancun, I learned too late that Mexico requires a notarized letter of consent signed by both parents for minors traveling alone or with one parent or guardian. If the parents are divorced, a copy of the parental custody agreement is allowed instead. The airlines enforce this rule before you get on the plane.

When you're shopping for alcohol on any Caribbean island, ask if there's a Kmart nearby. Often the dis- counter is a short distance from the docks where the cruise ships tie up and has an extensive selection at prices lower than the liquor stores on the main drag. While you're there, pick up that extra roll of film or the sunscreen you forgot.

The help of a concierge at an expensive hotel is available even if you're staying at a motel across the street. Go to the concierge with $5 (or whatever the assistance is worth to you) held discreetly but visibly in your hand. Chances are you won't be asked whether you're staying at the hotel. This worked for us once when we were stranded by a blizzard. We tried to rebook our flights on our own, but phones at the airlines were busy for two days straight. The concierge at a fancy hotel a few blocks away got through on his first try and managed to rearrange our flights for us.

Online check-in isn't just for airlines. After reserving an Alamo car over the Internet, I was offered online check-in just by entering my credit card number and driver's license information for approval. At the airport, following Alamo's instructions, I informed the shuttle-bus driver that I had checked in online and reserved an economy car. I was dropped off in the lot and told to pick whichever car I wanted. I drove it to the exit, where my credit card and driver's license were verified on the computer, and I was done.

Carry a Polaroid camera when traveling to developing countries. In Cambodia, several village children gathered around us, posed enthusiastically for pictures, and were fascinated by their images in our digital camera. We wanted to send them the pictures, but they were unable to tell us their address. Polaroids would have solved the problem!

When I called to book a hotel room in Budapest, I was offered a rate of $75 per night. After I told the concierge that I was looking for a room in the $35 range, he agreed to the lower price without much fuss. It sometimes pays to barter.

Here's an important tip for cruising in winter: Fly into the port a day or two before your ship is scheduled to depart. We booked a Costa Rican cruise but were stuck in New York, where all flights out of JFK airport were canceled. Itineraries that include stops in places with airports can allow people to catch up. Ours didn't.

Need a place for a laptop in your hotel room? Take the largest drawer from the bureau and put it upside down on the bed with the drawer front away from you. This creates a perfect-height desk for while you're sitting comfortably on the bed (you can even lean back on pillows), plus there's side space for papers, and the top leans toward you for easy typing or writing.

I travel with a mailing tube in my suitcase because I often buy paintings, drawings, and maps. My souvenirs always arrive home safe and sound. I just leave the mailing tube in my suitcase until the next trip.

I use an inexpensive, thumb-size USB flash drive to store medical and insurance contacts, confirmation codes, credit card numbers, addresses, and phone numbers. It fits in a secure zip pocket in my travel purse. If I don't have my laptop, I can insert the flash drive in most hotel or Internet café computers. Some USB flash drives password-protect your data, or you can download a free encryption program.

A company called Orikaso makes brightly colored polypropylene sheets that can be folded--kind of like origami--to form a dish, bowl, or cup. The sheets are lightweight and reusable, and you simply flatten them when you're finished. We found ours at a sporting goods store, but you can also buy them online. Check orikaso.com for retailers.

If you plan to leave a gratuity for hotel staff, follow our friend Phil's good advice: Give it at the beginning of your vacation, not at the end. He introduces himself to the housekeepers early in the trip and hands them a nice tip. Guess who always has plenty of coffee and fresh towels?

My husband packs Q-tips in a plastic cassette case. It's small and snaps shut, keeping the cotton swabs clean and dry.

Give your children a coach's whistle in case they get lost; put it on a ribbon so they can wear it around their neck. The piercing sound may be annoying, but you'll definitely find them quicker!

We've traveled to both Mexico and China in the last year and had the same experience in both countries: When we tried to exchange dollars to local currency, the banks wouldn't take bills with graffiti on them--telephone numbers, names, doodles, anything. Nor would they accept any bills that were torn or damaged. (We noticed a group from France having the same problem with their euros.) So before you leave home, make sure that any money you plan on exchanging is absolutely crisp and clean--or better yet, ask your bank specifically for brand-new bills.

During a visit to Mexico City, I was sitting in a plaza near a fountain, watching the locals stroll around in their Sunday best. Nearby, an older gentleman was playing a concertina; his music perfectly framed the scene. I took lots of pictures, but I didn't have a way to capture that music. Now I pack a small tape recorder along with my camera.

It's unnecessary to make a packing list for each trip. Instead, draw up a master list with everything you might need on any given trip--from ski goggles to snorkels, slippers to saline solution. Save it on your computer. Before you start packing, cross out anything you don't need for that particular trip.

A bike tour will offer a good introduction to a place, and you'll cover much more ground than if you were on foot. In Buenos Aires, for example, Lan & Kramer Bike Tours (biketours.com.ar) has a few guided itineraries that are fun for all ages and abilities.

If you don't have enough frequent-flier miles to get to Europe, use your miles to reach a major airport in the United States and then pay for the overseas flight from there. For a trip to Ireland, my husband and I used Delta SkyMiles to get from Cincinnati to New York's JFK airport and from there took Aer Lingus to Ireland. The Aer Lingus internet special was $267 per person. A Delta flight from Cincinnati to Ireland was $1,150 for two. We saved more than $600.

A beach ball can replace many expensive in-flight gadgets. Depending on how much you inflate it, the ball can function as a very comfortable footrest, a back support, or a lap pillow to support your book.

Read the fine print on your rail pass. You can often use it to save money on other modes of public transportation. With a Scandinavian rail pass, for example, you'll pay less to ride the ferries. In Switzerland, a rail pass can get you free bus rides, as well as complimentary entrance to museums and discounts on funiculars and hotel accommodations.

In order to keep track of my bags, I use a small metal bell--the kind dancers from India wear on their ankles. I thread it with fishing line and tie it to my carry-on. If anyone touches my bag after I set it down, the bell chimes. It's not a very obtrusive sound, but it's distinctive enough for me to notice if a thief is trying to get into my things. The same bell can be hung on the doorknob inside your hotel room.

Whenever I know I'll be renting a car, I pack a couple of folded paper towels and two small spray bottles--one filled with window cleaner and the other with Rain-X, a product that repels raindrops. It's hard enough driving an unfamiliar car in an unfamiliar location. At least with a clean windshield I'm able to see properly, no matter the weather.

Every year, I get address labels from numerous charitable organizations. I keep them with me when traveling because it's the quickest way to provide my address to new friends, enter prize drawings at shops, sign guest books, etc. It's not only efficient; it can also help spread the word about worthwhile charities.

You can enjoy free airport-area parking by staying the night before departure at an airport hotel or motel that offers park-and-fly rates. The cost of that overnight (which usually entitles you to two weeks of parking) is much less than what you'd otherwise pay at an airport parking lot.

If you plan to travel to a less-developed country, pack an extra suitcase with hand-me-downs of all sizes. Housekeepers and other resort workers make so little money that the clothes are greatly appreciated. On your way home, you can use that empty suitcase for souvenirs.

Spring skiing often means a wild temperature shift from morning to afternoon. If you want the option of removing outer layers or switching to a lighter ski jacket midday, attach the lift ticket to your clothing with a split-ring key ring. You'll be able to move your ticket as the weather warms up.

You won't always save by bringing the rental car back early. Alamo has an early-return policy at all of its locations, designed to discourage customers from returning cars early. If you show up at the lot a day or two ahead of schedule, Alamo will recalculate what you owe them at the daily rate; if it turns out to be less than what you would have paid for the week, they'll charge a $15 fee. Yet another reason to read the fine print on your contract carefully!

I always snap photographs of scenic highway markers, park entrance signs, and the like. These informational photos are put into our album to help identify the many sites that we visited.

I reverse the batteries in my portable CD player before packing it in my suitcase or backpack, in case it's accidentally turned on when my bag is jostled. I came up with the idea after arriving at my destination to find that the brand-new batteries I'd put into my Walkman were dead.