Hi Artu for Singaporean and Philippine you don't have to apply for a travel visa, Philippine and Malaysian nationals do not require tourist visas for a stay up to 21 and 30 days respectively. Singaporean nationality is also exempt from the usual visa requirement. One of my couch surfing friend who love to Hitch hike around the world drop me this advice for Vietnam if you decided to hitch hike this July.
Be prepared for minor scams from the border guards at the overland border crossings, especially at Koh Kong and Poipet.
Scam #1: Drivers and touts will insist that you need their help to obtain a visa. This is not true. They want to charge an extra fee. The visa process is easy, straightforward and do-it-yourself. Do not accept their ‘assistance' as it is not necessary and will only lengthen the process and increase the cost.
Scam #2: Immigration police may try to overcharge 100-300 baht for the visa, or charge 100 baht for the normally free exit/entry stamp. Try asking for a receipt.
Scam #3: Some Khao San Road based companies sell bus tickets promising transport from Bangkok to Siem Reap via Poipet. But instead the bus goes through the much more isolated Pailin crossing where passengers are subjected to more scams (overpriced visas, extra charges for transportation, change to inferior transportation, etc.) and have little recourse due to the isolation of the crossing.
When dealing with officials, there is usually room for polite explanations and bargaining. One sometimes-successful approach is to smile, say "no, thank you", smile some more, perhaps act like you don't understand and walk away. This technique may or may not work but it has a greater likelihood of success than simply refusing to do what they are asking or, even worse, becoming argumentative or showing anger. Hope that help if you intend to HH , hope that you find some couch surfing in Vietnam.
