Make sure you model proper pronunciation from the very beginning of the classes. Do so not only by making the students repeat the what they hear from a tape/CD. Pronounce the words yourself in many original ways e.g. as an old woman, as a soldier, as a baby, as an opera singer; whispering, shouting, laughing. Drill the students as a whole class, individually and in groups (boys and girls, left and right side, front row and back row). Whatever you do however do not exaggerate! If some students cannot copy your pronunciation, leave it and give them some time. Nothing is more discouraging than feeling different because of not being able to do what everyone else can.
