If you are a student then you may have very definite ideas about what you expect.  It is your expectations that are your guide when you are looking for a good singing course.  However, even though methods are very important there are so many you may find it bewildering.  This is especially so if you are a first time student or beginner.  It will be worth your while to choose a course that has been developed by a singing teacher who understands the needs of his students.  In particular, you want a course by a teacher who will give you a solid foundation to build on.