You'll be hard-pressed to make it to all French islands in one trip, as travelling between them is far from straightforward. Certainly, checking out two islands per visit is feasible - Guadeloupe and Martinique both have regular
ferry crossings between them, as do St Martin and St Barts.
The best way to get around each island is with your own wheels; what public transportation exists in Martinique and Guadeloupe is far from efficient, while St Barts - which happens to have the worst roads of the lot - has none whatsoever.
By bus
While getting around Martinique and Guadeloupe by bus is the most reasonably priced mode of transportation (¬1-¬3.50), the service is not for those in a hurry. Known as taxis collectifs (or "TC"), they're actually cramped minivans which generally run from 6am to 6pm weekdays, with scant service after 2pm on Saturdays and none on Sundays. There's no real schedule to speak of - they leave from the capitals when they're full. To board one outside the capitals, simply flag it down along the road; keep in mind, however, that TCs are often packed in the hinterlands. Tell the driver where you're going when you board and pay him when you get off.
By taxi
Taxis in the French West Indies are expensive, charging a minimum of ¬5 even if you're just going down the street, and doubling their rates Monday through Friday 8pm-6am and all day Sundays and holidays. Fortunately, the only time you're really likely to need one is to get yourself to and from your hotel and the respective islands' ferry docks or airport.
By car and hitching
Driving requires a good dose of fearlessness. The French drive like maniacs - especially in Martinique. Guadeloupe is slightly less harried but still necessitates that you be alert at all times, especially when driving in the busy capitals. St Barts has grown increasingly dangerous in recent years as the cars plying its narrow, mottled-cement roads have become both bigger and faster. Most
car rentals start around $50/day.
Hitchhiking is very common on Martinique and Guadeloupe due to the irregular bus service. The usual precautions apply.
By boat
The most common passenger boats are twin-hulled catamarans with a covered upper deck and an enclosed, air-conditioned lower one. Note that the trip from Guadeloupe to Martinique can be choppy. Unlike the buses here, ferries do attempt to follow a schedule of sorts, especially those making the 40min-1hr 30min crossings to Guadeloupe's offshore islands. The boats making the 1.5-3hr trips between Guadeloupe, Dominica and Martinique, however, rarely leave on time as passengers must acquire a boarding pass and go through customs beforehand, a badly managed process that requires a 45-minute minimum lead-time. Even if you've bought your ticket in advance - which is recommended for all sea passages - you'll still have to join the crowd in front of the quayside ticket wicket to procure your boarding pass.
By plane
There are several flights daily between the three islands, but don't expect efficient service. Much of the air traffic consists of twenty-passenger airplanes that rarely leave on time and have low cargo weight restrictions - you'll likely arrive without your luggage in high season. The fifteen-minute island hops between mainland Guadeloupe and its offshore isles are done by nine-seater planes with similar weight restrictions; more importantly, they may not take off at all if they're under-booked.
