To legally enter Vietnam, you would need to apply for a Multiple Entry Business Visa and should have a job lined up beforehand. Your prospective employer is responsible for filing a pre-authorization application with the Vietnamese immigration department on your behalf.
Once approved, a notification letter will be forwarded to the Vietnamese consulate in your home country, and they will issue a visa. Upon receiving your visa, you must apply for a work permit. The application, together with supporting documents, is processed by the Labor Department in Vietnam. Once approved and issued, both you and your employer are required to sign your employment contract.
The application process can take anywhere from 15 days to a month. The work permit issued to you is good for a length of your contract, and may be renewed up to a maximum period of 3 years.
By law, you are not allowed to start working until your work permit is issued, although some schools may ask you to do just that.
TEFL English teaching job listings in Vietnam
A general overview of what to expect teaching English in Vietnam
Detailed living costs for teaching English in Vietnam
Interviews with English Teachers in Vietnam
Vietnam Embassy USA(Visa Information)
Vietnam Official Website
Vietnam Tourism Information Page
Vietnam Tourism Guide
Vietnam Tourism Page
Vietnam News (VN Agency)
Vietnam News (Thanh Nien)
Vietnam News (Vietnam Net)