research as much as you can. A good place to start is.
Dog Breeding and Canine Reproduction by Debbie Jensen. Dog Breeding and Whelping guide for dog breeders.
Find a vet that is know small breeds and keep in contact with him. Less than 5 pounds is not idea to breed and alot of things can go wron. That is why you have a vet lined up and available 24/7
If you want to talk pm me or I will give you my number so we can chatt and help you with questions you may have.
Melissa