Obtain a computer program that teaches Vietnamese. Most such programs include audio compact disks, or CDs, to give you practice with hearing and pronouncing the language. Choose a program that best suits your needs and price range.
Insert the first audio disk into your car's CD player. Listen to the CD carefully and completely, following the prompts given to you. Phrases will be in both English and Vietnamese. You will be asked to repeat phrases, typically starting with those involving colors and numbers. Don't expect your pronunciations to be perfect; it's more important that you understand what you are hearing and repeating.
Use the computer program at home to confirm that you are pronouncing the words from the first CD correctly and that you are understanding the basics of the language. Use the time in the car as practice to increase your skill.
Listen to the second CD after you feel you have mastered the material on the first. Lessons usually are sequential and designed to help you absorb the material progressively.
Master each CD one at a time. Review previous CDs in their correct sequence on a weekly basis. Keep listening and practicing so you do not forget older material. Remember that learning a new, spoken language takes time and a lot of repetition.