I would like to add one thing that has helped me tremendously: I feel for the horse's inside hip. I weight his inside hip slightly with my seat. I "sit back" a bit on his inside hip as one of the most important parts of the canter cue.
The outside hind may officially start the canter stride, but the first push is made with the INSIDE HIND. If I feel that hip under me, he feels me over his inside hind, and will naturally want to make an extra effort with that leg, resulting in the correct lead.
So, here's how I do it: I bend the horse slightly around my inside leg at the girth in the direction I want to go, then sit back on the inside hip with my weight, then ask with my outside leg behind the girth. The horse is set up correctly and virtually always picks up the correct lead.
Now that said, I could go back and explain how I "bend the horse around my inside leg at the girth" in much more detail, but I'll assume I don't need to.
Last edited by Myya; 07-13-2013 at 12:51 AM.