Studying abroad provides the best way for you to immerse yourself in the culture and language. When studying abroad, you will be forced to rely on your language skills and will pick up the language much faster than you would living in the United States and learning it at your leisure. Ho Chi Minh City is the most popular destination for those looking to study abroad in Vietnam, with Phnom Penh and Siem Reapp a close second. American universities such as Suffolk and SUNY Brockport offer programs for students to study abroad. Independent programs like CIEE, SIT and Pacific Discovery also offer programs for those wishing to study abroad without the constraints of a university. Visit the link in the Resources for more information.
Larger universities such as Yale offer several levels of Vietnamese classes. Go to your local university's registrar or browse their courses online to see if they offer a Vietnamese course. Ask them about their policy on non-degree-seeking students taking a language class. If you cannot find a class through your local university, call a Vietnamese consulate for help. Visit the Vietnamese Embassies website (see References) to find locations in the United States. Classes are valuable, as they keep you on task and accountable for learning the language. You are also able to hear the teacher pronounce the words correctly so that you learn proper pronunciation.
Find a Vietnamese tutor through a Vietnamese heritage center or craigslist.org. This is a great thing to do individually or to supplement a class. It is preferable to find a tutor who is a native Vietnamese speaker so that you can be assured that you are getting proper spellings and pronunciation. You can also sometimes find Vietnamese immigrants who wish to trade Vietnamese lessons for English lessons. This is highly recommended, as sometimes teaching English will deepen your understanding of the way verbal communication works.
Find a group through a site such as meetup.com or a friend from your class who speaks Vietnamese. Go to these groups regularly or set aside a time during the day to speak to your friend only in Vietnamese. This will get your brain thinking in Vietnamese, and you can often learn new words through your friends or group.
The BMW of language software is Rosetta Stone, although the price almost equals the cost of a plane ticket to Vietnam itself. However, this software is very effective, and you can learn a great deal from it. However, you must be disciplined in order to succeed. The language program, no matter how great it is, will not learn the language for you. It is important that you spend time each day with the material.
For a cheaper alternative to Rosetta Stone, try the Pimsleur Language Program. The workbook and accompanying audio CD will help you learn the basics of the language. Like Rosetta Stone, it is important that you stick with the workbook and listen to the audio CD religiously, as simply owning the program won't magically make you learn the language.
If you are looking for just some quick Vietnamese phrases to use on your trip to Vietnam, Berlitz produces an excellent book and accompanying CD. Purchase this at your local bookstore or online.