Getting around when visiting Thailand poses no problems at all. In fact it's very easy and often very cheap. Buses are frequent and you can travel wherever you want on them. You can find places to buy tickets almost everywhere.
The most economical way to get around in towns and cities is without a doubt the bus. If you have problems using them and don't know which to catch, ask for help in the street. You'll always be able to find someone to assist you.
For an even cheaper option, climb aboard a songthaew. These are pickups adapted for use as share taxis. As with the buses, they travel on fixed routes. Pile into the back and remember to state your destination before climbing aboard to make sure you've got the right one.
Similar in style but faster and able to take you where you need to go are the tuk-tuks, a typically Asian form of transport. You need to haggle well before climbing in: prices are not fixed.
Taxis are the one other remaining option in towns and cities, and these are not very expensive either. Insist the driver puts the meter on or be prepared to be uncompromising when haggling.
When it comes to the longest journeys you'll have to make during your trip to Thailand, the ideal option is to travel by bus. These are fast and inexpensive. Of course prices increase in accordance with the category you choose. The cheapest are the government buses, which are especially worth considering when travelling short distances. To enjoy more comfort on long journeys, go for the private or VIP buses. On these you sometimes you get a meal served, most have a television and toilets, and all have the annoying habit of setting the air conditioning as cold as possible. Ensure you take something to cover yourself with.
Trains, though more expensive than buses, are actually slower, and they also have the disadvantage of not always running on time. Fares vary depending on the travel class and whether you choose a seat or a couchette. Tickets often have to be booked in advance.
For those with little time available, air travel is well developed in Thailand. Prices, which were quite low in the first place, have tended to reduce since the advent of low-cost airlines. These all compete fiercely with one another. Compare prices to take advantage of this situation.