We've been doing a lot of trot-canter-trot transitions, and occasionally walk-canter-trot. He doesn't quite understand the whole supporting outside rein at the canter yet, but I have been keeping that consistent at least. However, when I do that, the canter gets choppy, and he breaks every few steps down to the trot, no matter how much leg/seat I cue him with. He's only really "gotten" it about 3-4 times.
What else should I be doing?