Cubana airlines has an extensive domestic air network that services all of the regional centers, and flights within the country are not expensive, but prices have been on the rise. Most domestic flights are on smaller propeller aircraft, and they are 25% cheaper if booked in conjunction with your international ticket. Use your international cellular phone rentals to reserve an airline ticket.
Asociaciones de Transportes por Omnibus (Astro) operates Cuba's national bus service which links all the provincial capitals and many outlying towns once or twice a day. Foreign tourists now enjoy some priority on Astro buses, with four seats available for dollar sale on most departures. Apart from Astro, there's a hard currency company called Viázul, which requires all passengers to pay in dollars. Privately owned trucks (camiones particulares) have taken over much of the passenger transportation business, especially in eastern Cuba. Keep track of bus shedules by using your international cell phone rental.
The train system has deteriorated rapidly over the past several years. Although there are still some inexpensive, comfortable ruotes, particularly between major cities, bus is now the way to go. If you need to take the train, use your Cuba cell phone rental to reserve a ticket.
Cuba boasts Latin America's most extensive system of roads, and renting a car is definitely the easiest, if not the cheapest, way to see the country. Many Cubans hitchhike as a means of getting around and locally the activity is known as hacer botella (literally 'to make a bottle' with the hand). Government vehicles are legally required to pick up hitchhikers if they have the room, and town exits and major crossroads often have yellow-clad amarillo officials armed with clipboards to organize the Cubans waiting for a ride.