I don't train Sol with millet. For some reason there's no millet treats in Israel S: Only seeds and sticks of seeds mixed with honey. But Sol is CRAZY about them, so that's working anyway
Umm I put my finger next to his leg so he would step up. Each time he stepped only with the leg I wanted, he got a treat. Very soon he understood that he's getting rewarded for stepping with one leg. It was very clumsy, but I figured eventually it'll work out.
After seeing he got the concept, I put my finger in front of him, but maintained a bigger distance. He got rewarded once or twice before he understood that he shouldn't actually step on my finger. I was surprised he figured that out so quickly!
From the beginning I said "wave" every time. After he stopped stepping on my finger I changed the signal to a wave with my hand. Because he knew what I expected from him and how the command sounds like, he got used to the new signal immediately.
I hope I was clear enough! Good luck! ((