I'm using Denise Fenzi's method from Precision Heeling. Lots of disk and platform work for finding position. Aside from the detailed stuff in her class, she has many free videos on YouTube.
It's hell to understand from that blog post though It makes much more sense in her online class and in person. It's a really elegant method. I can adjust the difficulty for the dog in a lot of different ways and on the fly, I can fine tune details in a picture that isn't my final formal heel picture, there's lots of use to it. Gets you the most beautiful sit/down/stand out of motion, too.