The first big decision you have to make when planning a Caribbean vacation is which island to go to. The next question to answer, and it sometimes can be the most difficult one, is: "How do I get there?"

The problem is not so much in traveling to the big, popular tourist islands. Pan Am, Eastern, American, BWIA International and Air Jamaica fly jumbo jets regularly from the United States to these destinations -- among them, Antigua, Aruba, the Bahamas, Barbados, Grand Cayman, Curacao, the Dominican Republic, Guadeloupe, Jamaica, Martinique, Puerto Rico, St. Croix, St. Lucia, St. Maarten, St. Thomas and Trinidad. You usually can fly nonstop or at least without a change of planes.

Indeed, Air Jamaica will set the pace this winter for ease of travel to warmer climes with a weekly British Airways Concorde flight between New York and Montego Bay. Flying time? Just over two hours.

Things get trickier, however, if you are headed for one of the dozens of out islands, the little hideaways favored by frequent Caribbean travelers who are looking more for solitude than the bustling resort life. These are the islands where the larger airlines can't or won't fly because the airfield is too small or there are not enough passengers to make a profit. To get there, you jet to the nearest big island -- American and Eastern both have made Puerto Rico their major hub -- and then catch a connecting flight onward.

The out islands are served by more than 30 smaller airlines, together logging well over 1,000 daily flights. Unfortunately, some operate with a pioneering personality that can mean fickle schedules, broken seats, casual check-in and local produce stuffed among the luggage.

Nevertheless, adventurous travelers in search of new horizons happily hop onto the small-to-tiny planes (some of them single-engine puddle-jumpers that hold as few as three passengers). They have no other choice. These planes provide the only air service to the quieter islands of Anguilla, Tortola, Virgin Gorda, Carriacou, Dominica, Grenada, Montserrat, Nevis, Terre de Haut, Saba, St. Barthe'lemy, St. Eustatius, St. Vincent and some of the small Grenadine islands.

If their schedules are erratic, they do offer the compensating bonus of a bird's-eye view of island-studded seas.

About now, a third question should have occurred to you: What will it cost to fly to the Caribbean this winter?

If you are prepared to pack and go soon after you hear about a good deal, you will find bargain fares to some sun spots. But you will have to read the fine print in the offer -- many come with restrictions -- and be prepared to commit yourself to dollars and departure dates immediately. Often, you aren't entitled to a refund on bargain fares if you have to change your plans.

One way to find out about good deals is to read the newspaper travel ads conscientiously. An ad offering a bargain fare may appear only once or twice, and the first people who phone in snap up the few seats offered at the low prices. (They are, after all, only "come on" rates.) You can also consult a travel agent, who may know of other options.

American, Eastern, BWIA International and Air Jamaica are among the major carriers that fly to the Caribbean directly from Washington. But better fares sometimes may be available on midweek or pre-Christmas flights out of Miami or New York, both major departure cities for the Caribbean.

Many cheaper fares are linked to hotel packages. You have to commit yourself to one or more nights at a participating hotel to qualify for a deeply discounted ticket. A travel agent or an airline tour desk can help you with these packages. If you are interested in hopscotching between a number of islands, LIAT -- a major interisland carrier from Puerto Rico south to Venezuela -- has one of the Caribbean's best (but little known) bargain fares, the Explorer ticket. The ticket allows a month's travel for one fixed price, currently $327. Check prior to leaving home as to whether it makes better sense for your itinerary to buy the Explorer, available only outside the Caribbean, or another Explorer version, a multistop ticket offered for sale only in the Caribbean.

Here's a guide to getting to the out islands (and between them) from the following major hubs:

Antigua is home base for LIAT (Leeward Islands Air Transport) with small plane flights to Antigua's sister island of Barbuda and to neighboring Montserrat, Nevis and St. Kitts.

Nassau, the Bahamas. Geographically, the Bahamas are north of the Caribbean Sea but they get many U.S. travelers heading south to escape winter's cold. Nassau is the major Bahamian hub for Bahamasair, which flys to the Family Islands of Eleuthera, the Abacos and others.

Barbados is the hub for flights to St. Vincent, Grenada, St. Lucia and, with a couple of stops, to Dominica, as well as Tobago through Trinidad. LIAT is the most important interisland carrier out of Barbados, but there are also charter services from this airport.

Grand Cayman is linked with Miami and Houston by both Cayman Airways and Eastern. The two don't necessarily have the same prices for their flights, but Cayman Airways has an added bonus of including small Cayman Brac and Little Cayman in its ticket cost, although only when you specify those flights at the time of ticket purchase. Otherwise the satellite islands are an extra fare from Grand Cayman.

Guadeloupe and Martinique. From Guadeloupe, Air Guadeloupe flies to nearby Terre-de-Haut, la De'sirade and Marie-Galante, and farther north to St. Barthe'lemy and St. Martin's small airport at Grand Case, on the French side of that island. Air Guadeloupe also flies to neighbor Dominica and to the French sister island of Martinique, which lies south of Dominica. Charter services are available from the airport and LIAT flies through Guadeloupe as it does through Martinique.

From Martinique's modern airport at Fort-de-France there are links north to Dominica as well as to Guadeloupe, and south to St. Lucia, St. Vincent and the Grenadine island of Mustique. Air Martinique offers that service, as does LIAT in conjunction with Inter-Island Air Services.

Jamaica. Kingston airport (one of five airports in Jamaica) is home for Air Jamaica. Frequent, but not daily, flights stretch to Havana, Cuba, and to George Town, capital of Grand Cayman, as well as to Nassau and south to Barbados and Trinidad. Montego Bay is Jamaica's second international airport, and the primary airport for tourism. Domestic airports at Negril, Port Antonio and Boscobel (east of Ocho Rios) are linked by Trans-Jamaican Airways as well as charter and private planes.

Puerto Rico is the Caribbean's busiest and best-served airport. There are hundreds of daily flights on many regional airlines, linking Mayaguez and Ponce in Puerto Rico as well as Vieques and Culebra, Puerto Rico's satellite islands, and all the nearby islands -- including the Dominican Republic's cities of Santo Domingo and Puerto Plata. Flights to Vieques and Culebra leave from Isla Grande airport, about a 10-minute drive toward the city from the international airport.

Out of Puerto Rico's Munoz Marin International Airport, there are dozens of daily flights to St. Thomas and almost as many to St. Croix, aboard many local carriers such as Virgin Islands Seaplane Shuttle service, which departs from the runway and lands (on schedule) on the harbor seas at Charlotte Amalie (St. Thomas) or Christiansted (St. Croix).

Both American and Eastern have their small plane airline affiliates operating out of Puerto Rico. American flies its American Eagle service and Eastern links with LIAT and with its Metro-Express to fly to most of the islands to the east and south. Air BVI joins other carriers with flights to Tortola and Virgin Gorda in the British Virgins. It also flies out of Tortola to Anegada, one of the British Virgins. Crownair flies within Puerto Rico, even to the resorts of Palmas del Mar and Dorado, as well as to the Virgin Islands and elsewhere when expedient.

Since some of the Puerto Rican-based airlines change names almost seasonally, savvy travelers race immediately after arrival to the ticket booths that line one arm of the terminal. Shopping around for the next flight and the best price is often worthwhile since it's easy to get to any island in the northern Caribbean on small plane service from this airport during daylight hours.

U.S. Virgin Islands. St. Croix and St. Thomas are the major airports. St. John, the third U.S. Virgin, has no airport, although it does have air service thanks to the Virgin Islands Seaplane Shuttle, which sweeps into the harbor at Cruz Bay on its regular interisland service.

In addition to several charter planes, St. Thomas has Aero Virgin Islands, Crownair and other airline services from its airport and Virgin Islands Seaplane Shuttle service out of its harbor at Charlotte Amalie, the USVI's capital.

The same is true of St. Croix, which, because of its location some 40 miles south of St. Thomas, is a jump-off point for St. Barthe'lemy and St. Kitts for people who arrive at Alexander Hamilton Airport from U.S. mainland cities on nonstop American, Eastern and other major airline flights.

Dominican Republic and Haiti share the island of Hispaniola and are served by American and Eastern.

In the Dominican Republic, Puerto Plata is the international airport for the tourist-conscious north coast. Santo Domingo claims the international airport on the south coast. And a new airport at the east end's Punta Cana allows Club Me'diterrane'e charter flights to fly nonstop from U.S. cities.

In Haiti, you can fly from Port-au-Prince via local airlines to Jacmel in the south or Cap-Haitien in the north, although driving often is faster.

St. Maarten. Served by American and Eastern, this is the busiest hub for flights (and boat trips) to its satellites of Saba and St. Eustatius, each about 15 minutes away by air. There are departures also for St. Barthe'lemy, Anguilla (a seven-minute flight) and St. Kitts, Nevis, St. Thomas, Tortola and many other islands in its outer orbit.

The first four islands mentioned are easy day trips aboard Winair, Air St. Barths, LIAT or one of the other small airlines operating through St. Maarten. This is one airport where a few hours spent shopping prices and schedules can pay off. There are sometimes circle fares that bring multi-island flights to reasonable cost.

Trinidad. The larger of the two islands that make up the Republic of Trinidad and Tobago, it is the home for BWIA International and the southern terminus for many of the major airline flights. From the capital, Port of Spain, you can catch BWIA's frequent jet flights (12 minutes air time) to Tobago. LIAT offers the link to Grenada and Barbados, while proximity to South America gives Trinidad frequent flights to Venezuela's Maiqueta (Caracas) Airport, where change of plane can allow for flights to the southern triumvirate of Dutch-affiliated islands -- Aruba, Bonaire and Curacao.

Aruba and Curacao. Both are reached by nonstop flights out of Miami and New York. To reach Bonaire, however, you must make a plane change in one of the other two -- unless you board one of the scuba-focused flights sometimes scheduled from U.S. cities. If you plan to visit the ABC's, inquire before you leave home about any circle fares that link the three.

St. Vincent and Grenada. These two islands are situated at the northern and southern ends (respectively) of the several Grenadine Islands. Though not really hubs, they are the jumping-off points for interisland services to the Grenadines by boat and plane.

There are airstrips on the islands of Mustique, Canouan, Union Island and Carriacou, and LIAT's affiliate, Inter-Island Air Services, ties the string together. Charter planes also are available from Barbados, about an hour's flight away on a small plane. It is the most efficient (and most expensive) alternative.

Air service to the Caribbean began Oct. 28, 1927, when Pan American introduced a mail run between Key West and Havana, a five-hour flight. There have been a lot of changes since then. But it sometimes seems -- because of airport delays -- that the travel time to the Caribbean is about what it was in those early years.

The watchwords for today's vacationer: Plan for plenty of airport lingering, and tote carry-on luggage when you can.

Among the ways to ease the hassle if you are headed for an out island or plan to hopscotch between them:

Travel light, with only nonbulky carry on. The smaller planes have little storage space, and you may have to hold your luggage in your lap.

Research for day excursions to other islands as soon as you arrive at your first island. Since flights may not operate every day, getting to your chosen offbeat island may require juggling your schedule.

Do your research at the airport, where you can look someone in the eye. Information given over the telephone in the Caribbean -- on those times when you can get through on the phone -- may not be as reliable as your face-to-face research.

Ferreting out flights is a bit like a treasure hunt: It's often difficult and time consuming. Ask the same questions more than once -- and ask from several sources.

Acknowledge and respect island check-in times, even when you're required to check in an hour ahead of time for a 10-minute flight. Small people become big bureaucrats when they're behind an airline counter. On fully booked flights, relatives, friends and local politicians often precede you onto the plane -- even when you hold a confirmed ticket.

Margaret Zellers is the author of "Fielding's Caribbean 1988," "Caribbean -- The Inn Way" and several other books. She also writes the quarterly Caribbean Newsletter.