Tales from a parallel world.

India, Nepal, Malaysia, Cambodia, Thailand, Singapore.

Borders. In most Asian countries, a visa is issued online, upon arrival at the airport, or you can enter without a visa. But there are exceptions. For example, I haven't been able to get to Indonesia yet :( An approximate visa map looks like this http://www.visamapper.com/, but some data may be outdated, inaccurate, or missing.
Fingerprints. They are taken upon entry and exit in Malaysia (but entry into the country is visa-free and free), they should be taken upon entry and exit in Cambodia (but in reality, they are only taken upon exit). In Nepal, fingerprints are taken when purchasing SIM cards from some mobile operators (not all), and are not taken at the border.
Language: in India - Hinglish (Hindi + English, i.e., English with a wild local accent), in Singapore - Singlish, etc. In tourist areas, there will always be at least one local person nearby who understands English. In non-tourist areas, there may be language problems in Cambodia, Vietnam (although you can try to communicate in Russian there), and Indonesia.
Dress code. Europeans dressed in European fashion are generally treated normally, but if you are not going for a couple of weeks or to tourist areas, it is better to take into account the prevalence of Hindus, Buddhists, and Muslims and their views on how decent women (and men) should dress. In tourist areas, those dressed too carelessly may not be allowed to visit temples, for example.
White people in the eyes of the locals are walking wallets who are always happy to give money to the locals for no reason. In India, I was especially annoyed by their "Sir/Madam, please give me 10 dollars."
Tourist price. This follows from the previous point. For white people, all prices are quoted three times higher (some may even quote 10 times higher). But - good news! - this is Asia, and here you can, or rather, you must, bargain. Sometimes even in pharmacies and stores. Always - at the market and usually in transport. And no advance payments! Giving money before receiving the goods/service - you will be left without money and without the goods.
Work. It is practically impossible to find a job in Asia as an unskilled worker. A white-collar worker or a white-driver would look ridiculous. Although you can try to work as a guide or translator. Doctors, engineers, and artists with knowledge of English, and even better, the local language, can find good jobs. IT specialists usually work remotely for other countries, because other countries pay more than Asian countries can offer. There is also the option of working for six months in some America as a taxi driver or nurse, and spending the other six months in Asia.
Exotic food and local customs. In my opinion, the spiciest food is in India and Nepal. Then, in descending order: Thailand, Malaysia, Cambodia, Singapore. Local customs vary everywhere. But if you don't want to shock the locals, it is advisable to remember the "rule of the right hand" (give money with your right hand, eat with your right hand), and for Indochina, it is advisable to learn to eat with chopsticks - not all cafes for locals have forks. Also, in non-tourist areas, there may not be familiar and very necessary things like toilet paper. In tourist areas, there should be no problems with familiar household items. If the local food is too exotic, you can eat at "McDonald's", "KFC" and restaurants with European cuisine (in Nepal, in one of these restaurants, we even found chicken Kiev). You can also cook at home if you rent an apartment with a kitchen and stove or a room in a hotel with access to a shared kitchen.
Water. Locals drink from the tap, "white people" - only bottled water. It is also advisable to brush your teeth with bottled water.
Hospitals. Malaria, typhoid, diphtheria - are treated if not neglected, and you go to the hospital at the first symptoms. But it is expensive, so it is better to have health insurance. Dengue fever seems to be incurable, it goes away on its own, but they can relieve the pain. Hepatitis - I don't know, you can try to get vaccinated, or, like me, avoid everything potentially dangerous, drink only from disposable cups, and wash your hands 50 times a day.
And finally, Singapore is not Asia. It is an Asian branch of Europe. Although the locals call it the opposite - "Asia for beginners". Therefore, not everything written above applies to Singapore.