Accommodation and transport
Once there, you will need somewhere to stay. There is plenty of choice and you won't have much trouble finding a room even without a reservation. For peace of mind, however, it is best to book at least your first night in Thailand, as well as your nights in very popular destinations such as Phuket, Koh Phi Phi, Pattaya or Koh Samui, especially from December to February (
Agoda often has the best deals).
There are several ways to travel from city to city. The plane is the fastest and most expensive option, and only serves certain destinations
(see traveling by plane in Thailand). The train doesn't serve every city in the country; it is the cheapest but also the slowest option
(see traveling by train in Thailand). And finally, the bus is the most practical option: faster than the train, it can take you almost anywhere
(see traveling by bus in Thailand). For the islands, there are boats and ferries
(see boats to the islands of Thailand), and combined bus + ferry tickets are also available.