You should exercise the same due diligence when buying from a friend as you would from a breeder. Check what genetic conditions the puppy's parents were screened against, and how well socialized she was as a tiny puppy. Find out about the healthcare she has received to date (such as deworming and vaccines) and ask to see certificates as proof. Have her checked by a vet to make sure she is healthy. Finally, make sure her microchip registration is transferred into your name.