SEA is mostly very safe. Although you need to be smart, violent crimes against foreigners are rare. But theft and health issues are worth being aware of.
Scams
While mugging is relatively uncommon, there are many tricks people use to get your money. They often involve making you think the only way to solve an imaginary problem is by using their service such as: “The bus isn’t coming today because it’s a holiday. Here, ride on the back of my motorbike instead”.
Women on dating sites asking for money to help with some pretend emergency are quite common. This is more of a problem for older men because they’re an easier target and tend to have more money.
Fake goods are very very common. Fake cell phones that will break after 1 month, catch fire, etc. So don’t be tempted by phones being sold for a third the real price, because genuine phones cost roughly the same all over the world. Fake clothes, shoes, watches and handbags will be about the same quality as everything else around (i.e. pretty low) but certainly not as good as the real thing.
There will be multiple times when you spend more than you needed to. Try not to get too avoidant and untrusting as a result. If you’re too cynical you will miss out on chances to get close to people and benefit both parties.
Passports
Giving someone your passport means they have you in their power until they choose to give it back. Often this is unavoidable, but if possible give them a photocopy or financial deposit instead.
If giving them a photocopy, run two lines of ink through the photocopy. Write exactly what the copy is for "motorbike hire with XYZ" or whatever, then sign on the photocopy and date it. This ensures your photocopy can't be reused.
Rental deposit
If you’re renting from a private landlord (rather than a company that runs an apartment complex professionally) then it can sometimes be difficult to get your rental deposit back at the end of your stay. They know all they need to do is avoid you for a day or two until your flight leaves. A good way to circumvent this is to not pay the last month of rent and instead get them to take the rent money out of your deposit.
Alcohol and drugs
NOTE: none of the information in this section is intended to promote drug use, it is intended to minimize the harms that can sometimes occur.
Locally made spirits, especially in Bali (high import taxes make local spirits more attractive), are often distilled without proper temperature control. This means there can be poisonous forms of alcohol mixed in with the ethanol. People die or go blind regularly. In Bali they sometimes put local spirits into the imported bottle and lie to you when asked if it’s genuine. If you’re in a cheap bar, just be safe and drink beer.
Beer bottles in Philippines often come with a tissue wrapped around the top - use it to thoroughly clean the area where the cap attaches to remove the occasional corrosion.
Penalties for drug trafficking are extremely severe. If you indulge on such things check all your bags and pockets for stray joints or whatever else might have been forgotten before you cross a border.
In notorious party towns, (e.g. Haad Rin) where the full moon parties started), sometimes the police will work with the drug dealers. As soon as you buy something the police arrive, extract a large bribe from you and then share the money with the dealer. Do the deal quickly, leave the scene ASAP and don’t let them know which hotel you’re staying in. If the dealer is making phone calls or sending texts, get out of there right away. The police don't bother as much in places where drugs are not such a big part of the economy.
Tuk tuk drivers will often try to sell you drugs as they don’t make much money from driving.
In Cambodia what they call ‘coke’ is not usually cocaine, it’s methamphetamine. Don’t use that garbage.
Fake drugs are common in Gili Trawangan and Bali. Weed that looks right but smells like tea and does nothing, pills that do nothing or almost nothing, etc. Don’t bother with it; it's a waste of time and can often be extremely dangerous.
“Happy pizza” or “happy shakes”, containing marijuana or mushrooms are usually very strong. Drink half the shake, wait up to an hour and then have the other half if you still want more. Eat a couple of slices of pizza, wait, then have more if you'd like. However, sometimes in Cambodia you need to explicitly ask for them to make the pizza “extra happy” as they default to a no-weed version unless you pay a couple of extra dollars.
Philippines has a drug war in which 6,000 people were executed without trial in the last half of 2016 - about half of them by the police the other half by unknown vigilantes. This is probably the worst country in SEA to be involved with drugs or even be living in the same house as someone who is. No foreigners have been executed. The vast majority of the deaths are local people in slums so it is not much of a personal concern to foreign visitors.
Health
Hospitals and doctors
For small problems like needing some stitches, the local doctor will be cheap and effective. Facilities for treating tropical diseases such as malaria will be adequate. In fact, doctors in the west might never have seen dengue fever before and could make the situation worse. Pharmacies are very common and many drugs that would require a prescription in the west are available without one.
However in a serious emergency you need the option of being flown quickly to a good hospital that has the facilities required. Major cities like Singapore or Bangkok are well equipped and have well trained staff. This can cost tens of thousands of dollars, so travel insurance is a must. I've tried a few and WorldNomads has proved itself one of the top options. It is among the cheapest and people consistently say good things about them.
Some hospitals will refuse treatment until you can contact your health insurance provider and sort out payment. Save all the information (phone numbers, email addresses, policy number) into your phone so it is with you at all times. Don't assume your phone will have a data connection, so save it offline. If you want to be really sure, write it on a piece of paper in your wallet.
In Bali and Philippines the hospitals are not run very well. They will milk foreigners for all the money they have, even to the point of performing unnecessary surgery. If travel insurance is picking up the tab then flying out of there to Singapore, KL or Bangkok could save your bank balance and your life.
Food poisoning
It’ll get you eventually, about once every 6 - 12 months.
If symptoms don’t improve on their own after 24 hours, go to a pharmacy and describe what’s happening and they’ll give you some pills. Get some oral rehydration salts at the same time. Replacing all the salt you’ve lost will speed your recovery. One time I was too weak and lethargic to work for a week after a run of food poisoning, but recovered within an hour of drinking some rehydration salts.
If you’re really sick it will be difficult to go to a pharmacy and there might not be anyone else around to do it for you. So it’s best to be prepared have some rehydration salts and diastop in your bathroom kit. You'll be happy you were prepared when the time comes.
RSI
A quick look around any coworking space and you’ll see a whole lot of compromises being made by people hunched over their laptops. It’s fine for a few days or weeks, but it will cause you wrist, shoulder or back problems in the long run that can put you out of action for long periods.
Massages are cheap and readily available, so get your shoulders and back some much-needed rubbing. If you find a masseuse that is really good, try to get their phone number and make a private booking outside their normal work hours. It’ll be cheaper for you and they will earn more.
Your posture will improve dramatically if you raise your laptop up higher by using a stand like the Roost or Nexstand. You need the top of the screen to be roughly level with your eyes. You’ll also need an external mouse and keyboard to go with it, like mine shown here:
Raise or lower your chair so that your knees and elbows are at 90 degree angles. This takes strain off your wrists and improves leg circulation.
Vaccinations
If you consult with a travel doctor before leaving, they’ll want to inject you with many vaccines in order to eliminate any and all risks. This is fine, but the same vaccines can be found and given for much cheaper in SEA. The rabies vaccine needs to be done with 3 injections spread out over 3 weeks, so consider doing that before leaving home. However rabies shots can be had in Cambodia for $35 each so see what your home doctor charges to see if it’s worth it.
The two diseases most likely to mess you up are Malaria (only common on the border between Thailand and Cambodia) and Dengue, both of which have no vaccinations available. They are both mosquito borne, so use a weak deet-based insect repellant (especially in the evenings). If you’re using a strong concentration of deet (above 50%) make sure to thoroughly wash your hands before using your phone, camera, laptop keys, or any other painted or plastic items. The deet can and will easily melt off the paint or plastic, so be careful and warned. I’ve found a repellant with only 20% deet concentration was completely effective for long periods and did no harm to any paint or plastic.
Natural repellents based on citronella don't seem to be strong enough to deter tropical mosquitoes, but deet has some pretty scary health rumours associated with it. Try natural ones and see how they go for you.
Water
Buy water in bottles, don’t drink the stuff from the tap. If you’re going to be somewhere for more than a couple of days, buy the biggest bottle you can find and use it to refill smaller bottles that you carry with you.
If you want to be super safe then use bottled water to brush your teeth also. Lately I’ve stopped doing this and nothing bad has happened yet (fingers crossed).
Dogs
If you get bit by a dog, you should go to a hospital for a rabies injection - even if you have been vaccinated against rabies before.
When a dog is acting in a threatening manner, throw a stone in it’s direction and it will back down. They’ve learned the hard way about humans and stones. Even just pretending to pick up an imaginary rock is enough to make them whimper and run off.
Fumes / burning
During March & April wildfires burn out of control all over northern Burma, Thailand and Laos. Chiang Mai’s geography combined with the smoke leads to some very unhealthy conditions during this time, roughly equal to Beijing on a bad day. Buy a mask from HomePro (the kind used for toxic paints) and wear it while outdoors. Or you could just travel to Bali, HCMC, Koh Lanta or Bangkok during this time like many people do.
Try to get a mask which says P95 or N95 somewhere on the packaging - it's an internationally recognized standard for filtration. Having an air outlet valve is really important too in order to reduce the heat and humidity inside the mask.
You can keep an eye on the smog in Chiang Mai online. The site shows graphs of different particle sizes (PM 2.5, PM 10) and a combined estimate of severity called AQI. The Thai government considers PM10 levels above 100 to be unsafe while the EU and US set their level at 50 (for comparison, take a look at Beijing).
Throughout SEA people burn plastic rubbish along with leaves and whatever else is lying around. You don’t want to breathe that smoke in as it will contain dioxins. Try to hold your breath when it comes your way.
Safe motorbike riding
Motorbikes are the leading cause of hospitalizations and deaths among foreigners. In places with plentiful and cheap taxis there is no reason to risk your life, so don’t. But they are an excellent choice of ride in smaller towns or semi-rural areas for convenience and cheapness.
Drive slowly and don’t be impatient. It is very tempting to quickly weave through traffic. If you can't resist, stay with the flow of other bikes. Keep pace and don’t go faster or much slower than the rest of the herd.
Test the brakes before hiring the bike. Often rental bikes will be poorly maintained and one of the brakes will work fine while the other doesn't work at all. When braking, use both brakes equally to reduce the chances of skidding.
Expect other drivers to do stupid things - most of them were never given lessons and bribed their way into a license. Honk your horn the moment you feel the slightest uncertainty about whether someone has seen you or not - it’s not rude to honk like it is in the west.
When turning across the flow of heavy traffic, don’t stop in the middle of the road. If you do this you risk getting hit from behind. Instead, pull over on the edge and wait until it’s clear both ways before crossing.
Those lines of paint on the road are just a loose guide, so don’t expect vehicles to stay within their lanes.
There is a third virtual lane on a two-way road. It is in the middle for trucks and cars to pass motorbikes, regardless of what is coming the other way. Taking evasive action because someone coming towards you is using the third lane is a normal everyday activity. You need to be going slow enough that taking evasive action is not going to send you skidding off the road.
Driving style is a cultural thing, so try to adapt and fit in. That link goes to an article about Thailand, but it is applicable to many SEA countries seeing as they are variations on the same theme.
Taking people you don’t know very well to your hotel room
This includes that girl you’ve been chatting to online for 5 months. You don’t really know her until you've met in person.
Condoms - always. HIV is especially common in Cambodia.
After a night of passion, some foreigners will wake up with all their ID, cash, credit cards, laptop, camera, shoes, etc gone. Imagine the panic of being 6000 miles from home with no money to pay a taxi to even get to the embassy (which may or may not help).
Plan ahead and get organized before bringing anyone back home with you. Lock your stuff up. Ideally your place has a safe, but locking your valuables inside your backpack or suitcase will do. If your valuables are large then buy a bike chain from a hardware store and use that to secure the handles of your wardrobe. Before you go out, decide how much you’re planning on spending, double it (you want to have the option of going on a complete bender, right?) and leave the rest in a safe place.