English is not very commonly spoken here
In cities like Ho Chi Minh City and Hanoi, you will find plenty of English speaking people. However, in the villages and smaller towns, you are hard pressed to come across people who know more than a few English words. So it is a great idea to learn some common Vietnamese phrases and the Vietnamese words for a hotel, food, bathroom, petrol, etc.
Electricity, Money and Wi-Fi
The official currency for Vietnam is Vietnam Dollar (VND). VND is used most commonly, but some places accept USD as well. Vietnam does not have ATMs in remote areas and it is a great idea to carry loose cash stacked away safely. Exchange money from jeweler shops for better exchange rates. The plug points are all rated for 220V AC current. It is advisable to carry a universal travel adapter. Wi-Fi connectivity is quite good in Vietnam and you will find Wi-Fi in most public places and restaurants.
Be Prepared for the Weather
Due to its proximity to the equator, Vietnam experiences tropical climate. During the rainy season, torrential rainfall occurs and this may a damper for a lot of tourists. Carry plenty of summer clothes - loose, airy cotton clothes and large bottles of sunscreen. Carrying a light jacket and an umbrella is also advisable. Due to the tropical climate, mosquitos are found in abundance. Do not forget your mosquito repellant.
The roads are fairly dangerous
Vietnam has a lot of motorcycles on the road. Traffic rules in Vietnam are not very stringent, and many tourists may find it unorganised and difficult to crossroads. Walk with a steady and confident pace and do not stop anywhere. When you get over your initial shock, you will realize that Vietnamese drivers are considerate. Do not walk displaying your cell phone or other valuables as petty theft is rampant.
Napkins are not free
You may be used to the waiter getting you unlimited napkins and not having to pay a cent for it, but in Vietnam, that is not the case. Iced tea or Jasmine Tea is free as soon as you order off the menu, but each napkin costs VND 2000 or VND 3000. The waiters even linger at your table and count the number of napkins you have used.
Don't put your valuables on the table
Vietnam is a fairly safe country as long as you do not flaunt your valuables. There are innumerable cases of people losing their phones or wallets on seconds because it was in the table. Escape via motorbike is very common on these kinds of petty theft cases. Loop the strap of your day bag or purse under the leg of your chair. Keep your phone in your front pocket and don't limp-wristedly take photos in super-busy areas. Place your bag or purse between you and the driver, if riding on a motorbike. Be wary of any strange, sexy women approaching you at night. Don't let it all hang out.