The things we are currently struggling with is sending the dog out to a point behind the ball (the keep stopping to push the ball instead of going out to the target mat) and getting them to push the ball to us rather than all over the place. We're going to keep working at it and we will get there!
I've just started Treibball, but I used back-chaining to get him to push the ball to me and it worked really well - Starr picked up on it really quickly.
I'm really loving this sport so far, but it's tough finding resources!