Air   

There are many airlines operate regular domestic flights from Bangkok to major provincial and resort destinations. Advance booking is necessary when travelling during the high season and public holidays. For more information  

Rail

The state Railway of Thailand operates four train lines – Northern, Northeastern, Eastern and Southern – accessing nearly all major provinces.

Train fares depend on class of carriage and destination. Twenty-day rail passes are available for second and third-class carriages.

Hua Lampong (Bangkok Railway Station) is the main station. For more information  

Buses

Buses and coaches are the only mode of transport to access all provinces in Thailand, running both to and form Bangkok and between each other. Option included ordinary air-conditioned coaches and VIP air-conditioned coaches with refreshment services. Booking can be made through the following bus terminals:

- Mochit 2 Bus terminal, for northern and northern eastern destinations and Pattaya, Trat

Southern Bus Terminal,for southern,eastern and western destinations including, Pattaya Damnoen Saduak Floating Market and Kanchanaburi.

-Eastern Busterminal (Ekkamai) ,for routes to Pattaya ,Rayong,Trat and other points east.  For more information

Car Hire

Travellers with valid international driving license may choose to hire a car .English-language road signs and maps are commonplace. The Bangkok Yellow Pages list local and international automobile rental companies. Each offers different condition . Self-drive and chauffeur-driven automobiles are widely available.
International care hire companies such as Avis,Hertz and Budget operate in Bangkok, Pattaya, Hat yai, Phuket, Chiang Mai and on Ko Samui.

source: Tourist Assistance Center, Ministry of Tourism and Sports
                 (http://www.touristassistancecenter.go.th)