If I had to learn English as a second language, I think I would use the "total immersion" method. English has so many rules and exceptions to rules that students would have a difficult time learning it straight from a textbook. I learned to comprehend French and Spanish by reading their newspapers without an English translation.
The immersion technique involves watching actual movies and television shows where native speakers use the lines described in a textbook. If the chapter is on greetings, then the student will see dozens of American actors greeting each other, either formally or informally. That's a good way to learn how to fit into different social groups, since you wouldn't say "What's up?" to your boss or "How do you do?" to your new college friends. It helps to hear English spoken naturally.
The other good thing is that you can only speak English during an immersion class. This can be intimidating at first, but it does help a student think and respond in a new language.