Try using Bartok's Mikrokosmos. Those early books seem very well suited to a complete beginner.
... that's about all I know in regards to teaching.
I think you should start them out on some Rachmaninoff or Liszt. Great repertoire for somebody who's never touched the piano before
... Actually ... When I first started lessons, I practiced with the exercise books for about 2 weeks, then dumped them in my closet, and insisted that my piano teacher teach me some Rachmaninoff.
... and he did.
I learned how to play the piano, by studying Rachmaninoff's Prelude in C# Minor. I know it's a bit unorthodox... but I learned a lot more through that then those stupid exercise books could teach. I actually recently went back to look at them, and found that I learned everything in there without ever touching them.