Just a quick note for anyone reading the thread that the articles I provided links for have much, much more valuable information for teaching and for teachers getting started than merely information about what methods to use. The portions of the articles that cover methods are just a small, small fraction of the myriads of helpful information for teachers in the articles. Piano World has the link to the site (Piano Education Page) on Piano World's list of links to other sites. If there is a question about the source of the articles one can read the history of the site they came from: The Piano Education Page - Ten Years On
As far as methods, I have used Alfred's the past 8 years and Bastein some and looked over a lot of other methods at the music stores. As there is no perfect method, there are advantages and disadvantages to each. I see a lot of advantages in Alfred's, for example, but some disadvantages as well. I wouldn't bash any particular method to the point of telling a teacher not to use it but only make them aware of some of the "pitfalls" so that one can still use the method effectively by compensating. After one gets some experience with a method one begins to figure out what "problem" areas the method has and can use your own knowledge to compensate. That's the wonderful thing about this forum is that you can ask teachers here that have experience using different methods for advice on most effectively teaching from whatever method you choose. Whatever the drawbacks of these methods, I have gotten some good tips from reading about what others on the forum do in teaching from these that make them work effectively. The biggest thing to think about in choosing a method is choosing those that you feel most comfortable with teaching from and that work well with your students. I know teachers that use a combination from various methods and don't necessarily adhere to the same method for every student. A person can teach from you're own knowledge without a method as well. There are advantages and disadvantages associated with teaching from a method.
The best thing is you have this wonderful forum to ask questions as you go.