You could wait a long time for a teenager who's traveling to call home or even text. But there's another way to see what your kid is up to: Follow the money. Before sending teens off on a trip, make sure you have online access to any bank and credit card accounts they'll be using. You'll want to monitor their transactions anyway, to see that they're staying on budget, and to make sure their accounts haven't been hijacked by thieves. But there's another reason to monitor how the kids are spending their money: It will give you some clues as to their whereabouts and activities. Last summer, I sent my 16-year-old son and two other teenagers — without an adult — to six countries in Europe. They stayed in hostels, traveled by train, and none of them had cell phones. But by monitoring their ATM and credit card activity online, I could get a sense of their whereabouts. Did they make the overnight train from Barcelona to Paris? A record of a cash withdrawal from the Banque Nationale de Paris at a branch near the Eiffel Tower told me everything I needed to know. When their itinerary called for them to be in Germany, I saw a withdrawal from a Deutsche Bank ATM near the Berlin Zoo. On the day they were to travel by ferry to Denmark, there was a credit card charge in kroner. If I had to do it again, I would make sure, when sending a teenager abroad, that he or she did have a phone. But following the money gave me some peace of mind. Here are some other tips and advice for parents sending kids overseas, both from my own experience and from some experts. Money Book and prepay lodging, trains and planes in advance to cut down on the need for cash and credit. But kids will need some local currency in their pockets when they arrive, as well as a way to get more cash and charge expenses later on. Shop around for the best deals on foreign currency at home. My local savings bank offered the best conversion rate and no fee on the transaction. I sent each teen with cash to cover food and local transportation for three days. After that, they used ATM cards to get local currency wherever they were. Withdrawals should be made every few days instead of daily to cut down on transaction fees. Many parents buy prepaid, preloaded cards from credit card companies and other outlets that limit how much money teens have access to at any one time. Parents can reload the cards electronically from home. That way, teens “only have the money they need for the next day or two at most,” said Mike Bowers, senior director of health and safety for People to People Ambassador youth programs and a member of the Student Youth & Travel Association (SYTA). “And I have the added comfort of knowing where they're spending it, because I can see online where the expenditures are being made.” Another option: You can get a credit card on your account, with your teen's name on it. Just remember, you are responsible for all charges. Can you trust your teenager to refrain from a shopping spree? Remember to advise banks and credit card companies well in advance about cards that will be used overseas. If cards are not authorized for use in a given country at a given time, transactions may be blocked. Some countries now require PIN numbers with credit card transactions, and it can take a few weeks for credit card companies to process those PIN requests. Communication Your domestic cell phone carrier may offer a good short-term international plan or an international SIM card for your phone. Another option is to buy a cheap international phone. But these days, “most kids don't actually talk on their phones,” observed Patrick Connor, a vice president of SYTA and president of Director's Choice Tour & Travel, which coordinates performance tours for student musical groups. Instead, many teens prefer to text and post updates on Facebook, Foursquare or Twitter. That's a great way for parents to see what they're up to — as long as you don't mind not hearing their voices. Just make sure you inquire about international data rates for cell phones to cover texting and Internet service overseas. Personal safety Bowers tells students on People to People tours to “dress down and blend in. Leave your bling at home.” Connor tells his travelers to “make sure your purse and backpack are zipped; don't keep things in your back pocket or an open pocket.” Documents Make copies of passports, credit cards and the like so that if they are lost or stolen, account and serial numbers can easily be located and the loss can be reported. Make a master list of itineraries, including flights, trains and lodging, for both parents and travelers. Specify the names of train stations and airports, since some cities have more than one. STA Travel sells an International Student ID card for $22 that not only offers discounts to 40,000 museums, stores and other sites around the world, but also provides access to a password-protected website where you can upload copies of important travel documents in case you need to refer to them during your trip. Lodging Tour groups will arrange for lodging, but for students traveling on their own, hostels are a good option in many countries. Yet booking a hostel online, site unseen, can be confusing, even when using sites with customer reviews. For example, I wanted my son and his friends to stay in hostels that were not only safe and clean, but that were also centrally located. And in some cities, I wanted to make sure they were located away from red-light districts. In this case, a travel agent's advice was invaluable. STA Travel has contracts with hostels around the world that it inspects a half-dozen times a year, and the STA agent I used was knowledgeable enough to book hostels that were fun for young travelers, while offering environments that met mom's standards.