Let the mother have the babies on her one. One thing though, I know from delivering my dogs puppies, is that sometimes one will come out with a layering like plastic over it. Most puppies will break out of it, but if you see one struggling, just help it out.
Well your dog is going to be doing most of the work... just make sure the pups are coming out right and that none of them get stuck. If any of them seem to not be coming out right try to help them out. If you can't help it out then you need to rush it to the vet. In most cases the puppies come out just fine, unless the breed tends to have a larger head or the father was much larger than the mother. Ask you vet for more tips before she starts delivering.