Visitors from most countries do not need to apply for a visa before arriving in Thailand and will be granted a 30-day visa on arrival. Make sure you have a valid passport with at least six months remaining before it expires.
You’ll most likely be arriving at Suvarnabhumi International Airport, just outside of Bangkok . If you have a few hundred baht to spare (less than $10) and it’s not rush hour, your best bet in terms of convenience and comfort is to take a taxi into town.
The airport rail link opened in 2010 and offers express service to central Bangkok for 150 baht, which is a great option if there is traffic and you don’t have too much luggage. If you’re on a really tight budget but have time to spare, take an express bus from the airport to many of the most popular tourist destinations.
You can find nearly everything you need in Thailand at a reasonable price, including international health and beauty products, so don’t waste space in your luggage on shampoo or other toiletries.
Because of the weather, Bangkok  is a casual city, but people are generally quite style-conscious. If you don’t want to stick out too much, don’t disregard fashion sense just because you’re on vacation. It might be unfair, but visitors who look like backpackers get inferior treatment outside of areas such as Khao San Road.
When visiting temples you will be expected to dress more modestly: no shorts for men and women, and no sleeveless tops for women. In some Bangkok restaurants and nightclubs, you’ll be refused entry if you’re wearing anything that looks too casual. If you’re traveling during the rainy season, bring a lightweight rain jacket with a hood.