When travelling to Laos respect Laos culture and customs, dress respectfully. such as long trousers and sleeved shirts, when visiting temples and take your shoes off before entering temple buildings and private houses.
As with other Buddhist countries, showing the soles of your feet is very poor manners. Never touch any person on the head. Despite prevalent cheap alcohol, being drunk is considered disrespectful and a loss of face.
Things in Laos happen slowly and rarely as scheduled. Keep your cool, as the natives will find humour in any tourist showing anger. They will remain calm, and venting your anger will make everybody involved lose face and is certainly not going to expedite things, particularly if dealing with government bureaucracy.
Respect for monks is part of Laotian life, and the monks take their duties seriously. Remember that monks are forbidden to touch women. Some undertake a vow of silence, and will not answer you even if they can understand and speak English. It is best not to compel them to stand next to you for a photograph, or start a conversation if they seem reluctant.