Thailand is the country with left-hand traffic. Best way to move travel in the city is the public transport, because of chaotic and curious traffic comparing with European. Tons of motorbikes and the way people drive here can cause unpredictable and unwanted aftermath for your holiday. Best public transport you may find here is motorbike taxi or tuk-tuk (songteow).
In case you decide to drive yourself try on the parking lot first, adhering the left side then turn around and make few more laps. Keep in mind not to make any sharp motions and keep left side.
Highways and speedways cover almost all central part of Thailand. Quality of the main roads are pretty good, all damages are rapidly recovering. All highways are built using concrete block technology. Depending from road usage and purposes it could be covered with bitumen layer. In case of its absence you may hear knocks on block joints, not very loud and annoying. But overall roads cover is not ideal. Lot of places are under renovation now. Watch out sewer gates while rain which become slippery as an ice. Keep that in mind.