On your next Southeast Asia trip, don't fly in blind. Make sure you're prepared to handle the weather, culture, and travel conditions wherever you're headed.
The list that follows ought to help you prepare for your trip to Southeast Asia, although keep in mind it's a rather general list, covering a wide range of conditions in the region. Be sure to click on the following links for more fine-grained or country-specific information.
Get the Right Visa for the Country You're Visiting
Conditions for entry regarding US citizens vary widely throughout the region. Most countries in Southeast Asia allow fairly easy visa-free entry, or visa upon arrival, for stays ranging from two weeks to three months. Cambodia, for instance, also allows you to get an e-Visa online that negates the need to visit a Cambodian embassy or consulate.
The only fly in the ointment is Vietnam, which requires US passport holders to get prior visa approval at a Vietnamese Embassy or Consulate. Read about Vietnam's visa and requirements to get one.
For visa requirements in the rest of Southeast Asia, make sure to review this list of visa requirements for US Citizens in Southeast Asia (by country).
Set your Phone to Roam
Cellphone roaming in Southeast Asia is quite easy, assuming your phone meets certain criteria. At a minimum, your phone should be compatible with the GSM cellular standard, using the 900/1800 band.
Also, your cellphone provider should also allow international roaming; barring that, your phone should be SIM-unlocked to let you use local prepaid SIM cards. The latter option may be preferable if you're planning to do a lot of calling from abroad; roaming charges are often quite exorbitant.
Some websites are blocked in particular countries; a recent survey of Internet freedoms in Southeast Asia found that only the Philippines shared the same level of Internet freedom as the U.S., with others ranging only from "partly free" to the ominous "not free" in Vietnam, Cambodia, and Myanmar.
But you can tweak your phone to get past these restrictions.
Pack Right for Your Trip
For most destinations in Southeast Asia, light, loose cotton clothing will do for most destinations in Southeast Asia all year round. Most towns in the region are quite conservative (even cities), so wear clothes that cover your shoulders and legs when visiting temples, mosques, or churches.
Your packing list will depend on the time of year you're visiting. A traveler visiting Southeast Asia during the monsoon rainy season will want to bring clothes appropriate for the wet weather. Someone visiting during the summer seasons will want to pack UV-resistant clothes.
Whatever you do, do not bring controlled drugs into Southeast Asia. The region has the harshest drug laws on the planet, and even stuff that's been legalized in your neck of the woods may get you the death penalty if they catch you with your stash in Singapore's airport.
Get Insured Before You Go
When traveling to Southeast Asia, you should mitigate the obvious travel risks and get travel insurance. Many destinations are miles away from the nearest hospital or clinic. (For instance, if you get bitten by a Komodo dragon in their namesake national park, you'll need to be airlifted 300 miles west to a hospital in Bali. That's not a cheap ambulance ride.)
If something terrible happens to you so far from home, insurance can save you much-needed time and resources, as accidents, cancelled flights, or property loss can cost more than you could possibly afford.
Important note: Travel insurance will not cover you everywhere or in any situation: certain places and adventures will void your insurance if visited or undertaken!
Take Appropriate Health Precautions
Disease is an everpresent possibility in Southeast Asia - not just in the tap water, but particularly in the jungles and bodies of water representing some of the region's most-visited places. If you're not up to date on your shots, take time before your trip to get the right jabs in.
Bird flu (H1N1), while hardly on anybody's radar these days, can strike unexpectedly. Amazingly, flu is almost ridiculously easy to avoid, assuming the right precautions are taken.
The CDC is just one of many organizations providing travel apps designed to keep travelers safe; read about the CDC's online tools for healthy traveling to take in their tips and tricks.