The Vietnamese are a polite and peaceful people who extend a warm welcome to foreigners. They are tolerant of the inability of visitors to understand their country and will accept levels of behaviour and dress from them that would normally not be acceptable. However, a few things can sometimes cause offence.
To get on well with people in Vietnam ....
... don't tell them how to run their country!
Although not particularly politically inclined, Vietnamese people are very patriotic and resent the tendency of some foreigners to regard our country as 'backward' or criticise the communist system of government. The 'human rights' debate is not one-sided, nor is it as simple as some Western observers seem to think. It is not 'taboo' to discuss politics in Vietnam, but any sort of critical proselytising is likely to meet stony silence and may even lead to problems with the authorities. We Vietnamese paid a very high price for our independence but, by doing so, we won the right to run our country how we wish.
... dress respectfully!
Beachwear is a potential problem. Although not specifically prohibited, nudity is culturally unacceptable, particularly for Vietnamese women who are embarrassed by 'sexy' swimsuits and topless sunbathing. It will also attract unwelcome attention from Vietnamese men. Skimpy clothes, shorts and so on worn by either gender in temples and pagodas are also culturally offensive.
... don't expect 'Western-style' politeness
Some forms of Vietnamese behaviour may seem to be rude or unfriendly. For example, the Vietnamese don't understand the invisible 'no contact' comfort zone that people from the West automatically observe. Pushing and shoving in queues and on crowded pavements is commonplace.
Some older Vietnamese people avoid eye contact. In the West, this is regarded as an indication of shiftiness or dishonesty - here is traditional politeness to avert one's eyes downward as an expression of respect.
... be fair and reasonable
Being asked to pay an inflated price in markets and so on is normal - bartering is expected, but must be good-humoured to be effective. An attempt to push the price down as far as possible is not appreciated. Many people in Vietnam are still very poor - some of the people selling goods in the street earn only a couple of dollars a week. Visitors are in a powerful position - please pay a fair price, not the cheapest possible. On the other hand, paying an inflated price will make you look stupid in Vietnamese eyes, but you'll be very popular until your money runs out!
... don't get cross
Getting angry is a guaranteed way of losing 'face' and with it, respect. No matter how frustrating a particular situation might be, anger is a guaranteed way not to achieve your objective. Remember that 'the customer is always right' adage definitely doesn't apply in Vietnam. Aggressive complaining will usually be met with a wall of indifference.
... think before you complain
If a Vietnamese person makes a mistake - an error with your meal order or damaging your laundry, for example - please remember that, if you demand a refund or refuse to pay, the money will probably come from the pocket of the person directly responsible, not the business. A matter of principle for an irate tourist can cost a hapless employee a month's wages!
... don't be rude
Putting your fingers in your mouth when eating, or using a toothpick without shielding your mouth from view with your other hand, is considered rude. However, although both actions might upset some old people, the younger generation is much less bothered.
Gestures need particular attention. In the West, it is commonplace for people to cross their fingers to invoke good luck. In Viet Nam, this gesture represents the female genitalia and is the ultimate obscene gesture. Its inadvertent use, however well intentioned, will provoke considerable offence. Beckoning should be done with the palm facing downwards using the whole hand. Beckoning Western-style with the palm upwards is used only for young children and animals in Vietnam - doing it with fingers only is also an obscene gesture. It is highly insulting to beckon old people however you do it.
In Vietnam, public body contact is only OK between people of the same gender - a man can hold hands with another man, but to do so with a woman would be embarrassing. Vietnamese people recognise that foreigners behave differently and make allowances, but passionate kissing and similar behaviour will cause offence!
... and, most important of all, ...
... laugh and smile as much as possible!
Good humour will go a long way to resolving practically all problems between foreigners and Vietnamese.