Please note that everything mentioned below is subject to change. Because Myanmar's neighbours are excited to use the country as a trading hub, restrictions on border crossing may soon be reevaluated.
The easiest way to enter Myanmar is by air with a valid visa and passport. For up-to-date visa information, go here.
If travelling by land, you must walk across the border. You cannot drive a car or a motorcycle. Additionally, there is no train or bus connecting Myanmar to any country. If you choose to walk across the border, the only border you can cross into Myanmar to continue a trip throughout the country is via Ruili (Myanmar-China border). Every other point of entry leads to a dead-end, prohibiting you from free-travel throughout the country.
Mae Sai, Thailand:
Mae Sai is just north of Chiang Rai. From here, you can cross into Tachileik (Takeleak). Travelers are issued a 14-day entry permit (this is not a visa) at the border. You can travel only to Kengtung. Even if you have a regular tourist visa, you cannot go anywhere else. You can exit from this same place with either the 14-day permit or a permit from Myanmar Travel & Tours in Yangon.
From here, you can enter Myanmar on a "visa run", but this exit is closed to out-going tourists. A day permit is $10. Visitors cannot stay overnight in Myanmar.
You can enter Myanmar from here. Before your arrival, you can arrange a regular 28-day tourist visa in a approximately two days in Kunming, China. It is important to note that you cannot leave from here.
There is a border allowing entry into Tamu, but this entry is closed to foreigners.
Foreigners cannot enter Myanmar from any point in Bangladesh, India or Laos. Additionally, they cannot enter from any country via sea or river.
Due to changes in Myanmar's openness, there could soon be a route running from Danang, Vietnam to Mawlamyine, then through Moreh, India on to New Delhi.
Did You Know?
Myanmar is very rich in natural resources like petroleum, timber, tin, antimony, zinc, copper, tungsten, lead, coal, some marble, limestone, precious stones, natural gas and hydropower.