Once the pup is out be sure to get the bag off the pups head first, clear out the nasal passages and mouth of any fluids, rub the pup with a soft towel to stimulate it's breathing, then mom do some of the cleaning up on it herself & let it nurse in between births. It's a great bonding time and helps stimulate the following contractions.
Good luck and keep us posted. When are the pups due? We'll be watching and waiting to help if you have any questions while she is in labor.
http://www.debbiejensen.com this is a great website for whelping information