In my puppy packs I put lots of photos (mom, dad, babies through the weeks, grandparents famous relatives etc),
vaccination/ weight/health history of pup,
packet of food I'm feeding them with info and coupons if I can find any,
puppy pack from vet (include a Heartguard tablet and Frontline plus dose)
puppy care info,
copy of contract,
and all of my contact info.
The paperwork is in a paper folder with the new owner's name on it and I have everything else bagged ahead of time so I don't forget anything.
Also make sure you get multiple ways of contact (phone, cell phone, email, regular address, etc) for the potential buyers and keep it! I hate not being able to reach my puppy owners for updates due to changed numbers. I try to keep in touch a few times a year with past litter owners.
Aprille