
Airport Rail Link (Suvarnabhumi Airport)
Just landed at Suvarnabhumi Airport and want to go to the city? You can save money on taxis and travel by train. There are two train services at the basement of the airport.
City Line
Price: 45 baht
Duration to Phaya Thai station: 30 minutes
Frequency: 15 minutes
Express Line (Non-stop service, straight to Makkasan station)
Price: 150 baht
Duration to Makkasan station: 15 minutes
Frequency: 30 minutes

BTS / MRT
This is the easiest way to get around Bangkok, avoiding all traffic jams. BTS and MRT is well connected to all major areas. Only thing is that you have to do some walking. But it is worth it as you may be stuck in a jam for an hour or more if you do not take this form of transport.
Download the Network Map here.
If you are travelling in a group, it may be cheaper if you travel by taxi. But bear in mind you might be stuck in the jam.

Taxi-Meter
Taxis are everywhere in Bangkok. Always ensure that the driver agrees on traveling by meter before boarding. From September 2012, there is a new law stating that all taxi drivers must accept all passengers and must turn on the meter. It is an offense not to do so.
Some taxi drivers may tell you that the place that you want to go is closed and suggest bringing you to another place. Also reject and do not accept their offer. They like to tell passengers that yaowarat, somboon seafood, RCA is closed and in the end bring you to places where they can earn a commission. Be persistent and stick to your destination.

Tuk Tuk
Tuk Tuk is usually more expensive than Taxi as they do not run by meter and hence will always quote you a very high price. Be sure to bargain. If you know the rough price of the area you are going, you can bargain to a price where you are comfortable.
If you have not taken Tuk Tuk before, do try it at least once. Its fun and thrilling, just that you will have to bear the fumes from the exhaust. Not a very clean journey to your destination if its raining!
At times, taking Tuk Tuk is faster as they will go by shortcuts. Especially during peak hours at Siam Square area, it is very hard to get a cab back to Pratunam. Hence I would opt for Tuk Tuk for the fastest alternative, paying him around 80 to 100baht.
Usually older drivers who wear the blue or grey shirt are more honest and will be willing to take you. Many young drivers will just quote you an atrocious price.
Scam Note: Some tuk tuk drivers may tell you that they can bring you to MBK for 20 baht. Do not ever board! Once you board, they will tell you that MBK is closed and will bring you to some jewellery place where they will get commissions. Hence, do not board when its too cheap and when its too expensive. Want to escape all this hassle, take the taxi!