In Vietnam, as well as in China and Japan, it is important to give and receive items with two hands. It is not enough to do so with the right hand – it must be both hands together. Using both hands at the same time suggests you are giving full dedication to the item or transaction at (and in!) hand.
In Asia, the exchange of business cards is particularly important – a kind of opening ritual. Not presenting your business card can be seen as a sign that you are withholding something or that your business is not completely genuine. Make sure you have cards printed before you go to Vietnam and that you have your card at the ready – held with both hands – as soon as you enter and start exchanging greetings.