Hard question to be honest mate I think the main thing to do is keep calm,with my older dog she never got the hang of retrieving until I done more than 3 retrieves just continuous with the tennis ball but not so she got bored the other thing I done with her which help is short retrieves so I would throw the tennis ball to her through the air close by and then she just pass it back just a few suggestions,now I find retrieving one of the hardest things to get bang on with a rabbit and the best retrievers I've seen have been the natural ones where the lads who had them didn't do anything retrievi