The first twenty four hours: a checklist.

Before you fly

In the terminal, before you leave the building

• Get connected. Activate the eSIM or buy the SIM at the counter, and confirm it works before you walk away from the counter.
• Get cash. Use an ATM or an exchange counter for enough baht to cover the first day, and specifically ask for or break into small notes. Taxi drivers, tolls and market stalls cannot change a thousand baht note.
• Check the passport stamp. Look at the date written in it before you leave the immigration hall. A stamping error is trivially fixed at the desk and a serious nuisance later.
• Keep the arrival documentation. Whatever paperwork or confirmation you were issued, photograph it and keep it with the passport.
• Take a trolley. They are free at both Bangkok airports and there are plenty; do not pay anyone for one.
• Walk past everyone offering a taxi. Your car has your name on a board, or you are going to the signposted public taxi rank downstairs.
• Message whoever is expecting you, before you leave the building, while you know the connection works.

Money in the first day

Thailand is far more card friendly than it was, and Bangkok in particular runs on QR payments, but the QR system generally requires a Thai bank account and is therefore not available to a short stay visitor. So cash still matters, and specifically small denomination cash. Plan on carrying a working float and topping it up rather than making one large withdrawal and living on it.

• Thai ATMs charge a flat fee for foreign card withdrawals, currently in the region of two hundred and twenty baht, on top of whatever your own bank charges. Withdraw larger amounts less often.
• Always decline the ATM's offer to convert to your home currency. Choose to be charged in Thai baht and let your own bank do the conversion; dynamic currency conversion is consistently the worse rate.
• The downtown exchange bureaux, including the long established chains around Silom, Ratchaprasong and Pratunam, generally offer better rates than airport counters or hotels. Change a small amount at the airport and the rest in town.
• Carry twenties, fifties and hundreds. This solves taxis, tolls, markets, tips and the coffee.
• Keep cards and cash in two separate places, and keep one card that never leaves the room safe.
• Cards are accepted in hotels, malls, restaurants and larger shops; assume cash for taxis, markets, street food and small independents.

Water, ice and eating on day one

Do not drink the tap water. This is not alarmism; Thai residents do not drink it either, and bottled water is inexpensive and everywhere. Hotels supply it, convenience stores sell it in every size, and a household on a longer stay orders large bottles by delivery. Use bottled water for drinking and for cleaning teeth if you are cautious in the first days, and let a sensitive stomach adjust gradually.

Ice is a different question and the honest answer is that commercially produced ice, which is what established restaurants, hotels and convenience stores use, is made from treated water and is generally fine; it is the uniform cylindrical ice with a hole through the middle, or clean crushed ice from a sealed bag. What deserves more caution is ice from an unrefrigerated bucket at a roadside stall in the heat. On food, the general rule is that busy is safe: a stall with a queue turns its ingredients over fast. On the first day, after a long flight and a change of climate, eat something simple and modest rather than the best meal of the trip, and save the ambitious dinner for the second night when you have slept.

Power, plugs and the practical room

One adapter per person is not enough; one adapter powering a four socket travel strip is the arrangement that works, because Thai hotel rooms rarely have as many accessible sockets as a modern family needs. Buy the strip before you travel.

The pharmacy list

Thailand's pharmacies are excellent, plentiful and staffed by qualified pharmacists, and the large chains are in every mall and on every high street. A great deal is available over the counter, which is convenient and also means restraint is required: do not self prescribe antibiotics, and see a doctor for anything beyond the ordinary, because Thai private healthcare is fast, good and much easier to access than most visitors expect.

• Oral rehydration salts. The single most useful item in a hot climate and the first response to any stomach upset.
• Paracetamol. Familiar, cheap, and the sensible general painkiller.
• An antihistamine, for insect bites, unfamiliar plants and air conditioning reactions.
• Insect repellent containing DEET or picaridin, and a plug in repellent for the room if you are near water or greenery.
• Antiseptic cream and plasters. Small cuts need attention faster in a humid climate than at home.
• Motion sickness tablets if boats or mountain roads are in the itinerary.
• High factor sun protection and after sun. The sun here is stronger than it feels under cloud.
• Your own regular prescriptions in their original packaging, with a doctor's letter. Some medicines that are routine elsewhere are controlled in Thailand; check before travelling with anything unusual.

Registration, and the paperwork nobody mentions

Thailand requires accommodation providers to notify immigration of foreign guests staying with them, within a short window of arrival. If you are in a hotel, a serviced apartment or a registered guesthouse, this happens automatically and invisibly and you need do nothing. It becomes your concern only if you are staying in a private residence, a friend's condominium or a villa let privately, in which case the responsibility falls on the owner or the person in possession of the property, and the practical step is to make sure they have actually done it. It matters later: the notification receipt is one of the documents that can be requested when extending a stay or dealing with immigration.

Alongside it, keep the passport and the entry stamp accessible for the first few days, photograph the passport photo page and the stamp, and store the photographs somewhere you can reach without the phone. Anyone staying long enough to need an extension, a bank account or a driving licence will be asked for these repeatedly, and having them already digitised turns a two hour errand into a ten minute one.

Before the first evening

Three things, and only three, need to happen before you go out on the first night. Have the accommodation's address in Thai script on your phone and know how to show it to a driver; this is the single item that prevents the classic bad first evening. Have small notes in your pocket. And have a working data connection with the map application tested, not merely installed.

• Save the emergency numbers into the phone: 191 for police, 1669 for medical emergency and ambulance, 1155 for the tourist police who operate in English.
• Note the nearest private hospital to where you are staying. Bangkok's private hospitals are outstanding and knowing which one is ten minutes away is free insurance.
• Set the phone to local time and, if the flight was long, force yourself to the local evening rather than sleeping at four in the afternoon. One disciplined first day removes three days of jet lag.
• Fill the room's water supply and put a bottle by the bed. Dehydration in this climate is quiet and it is the usual cause of a bad second day.
• Confirm tomorrow's first arrangement in writing tonight, with a pin, rather than at breakfast tomorrow.
• Photograph the hotel's business card, the room number and the wifi password together in one image.
• Walk somewhere close for the first meal. The first evening is not the night to cross the city.

Entry requirements, arrival card procedures, registration obligations and ATM fees are set by Thai authorities and banks and change without much notice. Verify current entry and arrival card requirements with the Thai Immigration Bureau or the Royal Thai Embassy in your country before travelling, and confirm accommodation registration with your hotel or the property owner on arrival.

This briefing is general information, not legal, tax or investment advice. Thai rules change frequently and individual cases differ. Verify current requirements with the relevant authorities, including the Immigration Bureau, the Board of Investment, the Land Department, the Department of Business Development and the Revenue Department, and take advice on your own facts before acting.