If you're living and working in Thailand, there are quite a few and relatively cheap options for getting around. Like many countries, it's always adviseable however to apply for an International Driver's License prior to heading abroad. Always better to be on the safe side.
Some of the more popular means of transportation are:- Songtaew
These are small pickups fitted with benches along the side. They operate like buses, picking up and dropping off passengers as they go along, except that they have no fixed route. You need to flag one down and find out if your destination is on the way before boarding.
- Motorbike
Motorbikes are the most common transportation in Thailand and the easiest and cheapest way to get around. Popular amongst many English teachers whom buy a 2nd hand motorbike within their first few months of arriving in Thailand.
To rent a motorbike - or car for that matter - you must have a valid driver's license from your country. Rental is normally between Bt120~Bt150 during the low season and Bt150~Bt250 during the high season for a standard motorbike.
It's also common to see many riders without helmets. Even some of the police on their motorbikes don't use helmets.
- Car
Driving in the populated areas of Thailand is not easy. A use of force and ignoring other traffic seems to be the only way to weave your way around. Best not to drive a car in Thailand and keep life simple. 
- Motorbike Taxi
Motorbike Taxi drivers are usually dressed in an orange vest and are available for a short trips. Simply wave one to a stop and ask for the fare to your destination. The price is normally Bt20.
- Tuk-Tuk
Almost all tuk-tuks in Thailand are small Daihatsu and Isuzu pick-ups remodelled with seats and a roof to fit their new purpose. Tell the driver where to go, ask him for the price (don't forget to haggle) and climb into the back.
- Longtail Boat
Longtails are available on most beaches for short sightseeing trips. Rental rates range from Bt400 to Bt1,200 depending on the destination.