Ask your physician to recommend a specialist near you, or contact the International Society of Travel Medicine; fax requests to 770-736-6732. Who gets bumped first from a flight? Those who check in last, who check in late (less than 10 minutes before a domestic flight departs, 20 minutes on an international one), and who haven't reconfirmed. Passengers flying on discounted or frequent-flier tickets might have lower priority on some airlines, particularly international carriers. Nevertheless, everyone is entitled to compensation for involuntary bumping. How can you tell whether a travel offer is a bargain or a scam? You can't, usually, but there are several red flags: Were you "specially selected"? Did they ask for your credit card number? Did they request vague deposits or registration fees? Was an immediate answer demanded? Or did you have an unusually long time to accept the offer? Some offers are not scams per se but require that you sit through a sales pitch for a time-share purchase-not necessarily the worst sacrifice to make for a cheap vacation. Is there a publication with detailed information on frequent-flier programs? The Official Frequent Flyer Guidebook lists all major airlines, along with their partners, affinity charge cards, and awards requirements (800-487-8893; $19.95); Web sites such as Biztravel.com and Insideflyer.com help track mileage and program promotions. Where can I find cheap airfares? Travel as a courier or book with a consolidator. Being a courier requires a flexible schedule and means you can fly with carry-on luggage only (call the International Association of Air Travel Couriers for companies: 407-582-8320). Consolidators may be found in the tiny ads in the back of newspaper travel sections. To avoid the shadier ones, find out how long the company has been in business and whether it accepts credit cards, and check for complaints with the local Better Business Bureau. Some travel agents work with consolidators; if yours doesn't, suggest one to your agent that's affiliated with the American Society of Travel Agents (703-739-2782). The Internet is now a resource for bargains, offering short-term promotions and lastminute sales for weekend travel, in particular. Sign up to receive free e-mail notices via the airlines' Web sites. What are the best insect repellents? Those that have the active ingredient deet, or diethyl toluamide; these are applied topically and sold in campinggoods stores. Other repellents contain permethrin, a chemical soak for clothing that doesn't stain or smell; the potency lasts through two washings. What is the best way to "pop" your ears in flight? All the folk remedies apply herepinch your nose and blow, yawn, or go through any other manipulation that will force the eustachian tubes to open. If you're prone to problems, try not to sleep during takeoff and landing or you won't be able to do those facial things that help relieve the pressure. How can you get tickets to the Kentucky Derby? Write to Churchill Downs at least nine months before the May event (Churchill Downs Derby Office, 700 Central Ave., Louisville, Ky. 40208), or call for more information about general admission for the grandstand courtyard and infield (502-636-4400).

How to A your own Q Many of the questions sent to the Q&A column can be answered with a few well·placed phone calls, letters, or faxes. Here are a few of our favorite resources: Most countries have tourism offices and consulates in major U.S. cities (usually at least in New York and Los Angeles) that distribute information about hotels, transportation, special events, and visa requirements. Most U.S. cities and states also have tourism departments or visitors bureaus that provide brochures and activities calendars. For information about basic consumer airline rights, order the booklet "Fly· Rights," from the Consumer Information Center (Dept. 1338, Pueblo, Colo. 81009; send a check for $3.00, payable to the Superintendent of Documents). To find out what vaccines are required or recommended for particular countries, call the hot line at the Centers for Disease Control and Prevention (404·332·4559). For help in mediating disputes or to find a member travel agency that abides by the American Society of Travel Agents code of ethics, call ASTA (703·739-2782); call the U.S. Tour Operators Association (212·599·6599) or the National Tour Association (800·682·8886) to find a member that is bonded for liability insurance. Updated travel warnings and consular information sheets on particular countries are available from the U.S. State Department's Office of Overseas Citizen Services (202·647·5225) or its Web site (www.travel.state.gov). To find out about travel resources for the disabled, contact the Society for the Advancement of Travel for the Handicapped (212-447-7284). To find a tour operator or travel agent who specializes in a particular region or type of vacation, order the Specialty Travel Index (415·459·4900). For value added tax refunds, contact Europe Tax-Free Shopping (203·965·5145).