Research your destinations to decide where you want to visit when you travel to Thailand and Cambodia. This will influence how long you have in each country and when you want to move on. Cambodia's main attraction is the Angkor Wat temple complex; an ancient heritage site on the edge of the developed city of Siem Reap. Sihanoukville has wide sandy beaches and Phnom Penh is one of Cambodia's colonial-style cities with shops and restaurants. In Thailand your destination will be based on your preferences and whether you want to trek in Chiang Mai, visit the beaches and spas on the islands of Phuket and Ko Samui or relax on Khao Lak and Ko Phi Phi.
Decide when to go. Consider the weather and how it will affect your vacation. The best time to visit Thailand is between November and February when temperatures are cooled by the northeast monsoon. Good months for Cambodia include December and January with lower humidity levels. This is also the peak tourist season. Travel in the rainy season -- July to October -- for cheaper prices and some downpours.
Choose your flights. Book a flight into Bangkok for the biggest choice of flights and largest range of deals. Travel to your favored destinations within Thailand before making your way to Cambodia.
Choose your transportation from Thailand to Cambodia. You can take a flight to one of Cambodia's two international airports, Phnom Penh and Siem Reap, or cross into the country from Thailand by bus at one of Cambodia's six international border crossings. The most popular is the Aranyprathet/ Poipet border crossing. Traveling to Cambodia overland is the cheaper and more adventurous option.
Seek medical advice regarding the vaccinations you need to travel to Thailand and Cambodia, four to six weeks before you travel. The Centers for Disease Control and Prevention suggests you make sure you're up-to-date with shots such as measles, mumps, rubella, diphtheria, pertussis, tetanus, poliovirus vaccine, hepatitis A and B and typhoid. Research and buy comprehensive travel and medical insurance or make sure your current insurance is up-to-date and covers the areas you want to travel to.
Buy visas. Check the Thailand visa situation with your airline or the U.S. Bureau of Consular Affairs. Visa requirements change frequently, but in 2010 if you entered Thailand by air as a tourist you are eligible for 30 days' travel in the country. If you're crossing by land at Aranyprathet/ Poipet you can get a Cambodian visa on arrival but eVisas are available in advance, a convenient option considering the sometimes chaotic border crossing.
